Hulk Hogan versus Andre the Giant. WCW versus The nWo. Sheamus versus Alberto Del Rio. In the pantheon of great sports-entertainment rivalries, new and old, matters are often settled through a series of epic battles. But sometimes, the game's most legendary competitors cross paths on only one occasion.

WWE Classics dug up classic encounters that only took place once, but we wish they could have happened again under different circumstances. Here are nine matches that deserved a sequel.

( WATCH VIDEO PLAYLIST | VIEW PHOTO GALLERY)

WWE Champion The Rock vs. Eddie Guerrero: Raw, July 22, 2002

One night after winning the Undisputed Championship for the first time ( WATCH), The Rock arrived on Raw to address the WWE Universe. But before he was able to speak more than just a few words, The People's Champion was shockingly interrupted by Eddie Guerrero. Each Superstar was no stranger to trading verbal barbs, and after a contentious exchange, the two electrifying competitors agreed to meet in the main event later that evening. If Latino Heat was successful in defeating the champion in the non-title bout, The Rock would put the championship on the line the following week.

The match was as thrilling as would be expected. Guerrero was impressive, manhandling The Brahma Bull on several occasions. But after the cruiserweight great missed his signature Frog Splash, The Great One was able to catch his foe with a ring-shattering spinebuster and People's Elbow for the pinfall victory. ( WATCH) Eddie and Rocky met twice over the following month in tag team competition, but the two all-stars never again met in a singles encounter. By the time Eddie had climbed back up the ladder and became WWE Champion in 2004, The Rock was no longer a full-time active performer.

( MORE ROCK | MORE EDDIE)

Rey Mysterio vs. Sabu - Extreme Rules Match for the World Heavyweight Championship: ECW One Night Stand 2006

More than 10 years after the two highfliers clashed in six-man battles in AAA, a lucha libre organization based in Mexico City, Rey Mysterio and Sabu met once again. And at ECW One Night Stand, it was for the World Championship.

Sabu had not appeared in WWE in the decade since ECW invaded Raw, but he re-emerged as part of ECW's rebirth in 2006. Scheduled to face Mysterio for his World Title at New York City’s Hammerstein Ballroom, Sabu made several appearances on WWE programming to prepare for the upcoming championship bout. On the pay-per-view, both Joey Styles and Tazz — a longtime Sabu rival — declared the bout a “dream match.”

Rey was no stranger to ECW rings, having made a name for himself in the States during the mid-1990s in his Extreme battles with Psicosis. (WATCH REY VS. PSICOSIS: MATCH 1, MATCH 2,  MATCH 3) But now Mysterio was representing SmackDown, and Sabu was the revered wildman. The two risk takers pulled out all the stops and the Extreme maniac treated the crowd to his unique brand of aerial maneuvers. Late in the contest, Sabu prepared a table draped across the ring apron and guardrail. With his opponent on top, the Arabian madman executed a triple-jump DDT through the table. Though the maneuver was legal under Extreme Rules, the bout was declared a draw due to feared injury sustained by both men. ( WATCH)

The hardcore faithful clamored for a rematch, but the two innovators never appeared in a ring together again.

( MORE MYSTERIO | MORE SABU)

The Undertaker vs. Ric Flair - No Disqualification Match: WrestleMania X8

Any sports-entertainment historian or member of the WWE Universe could argue that the The Phenom and The Nature Boy are perhaps the two most legendary figures in the history of the squared circle. But before WrestleMania X8 at Toronto's SkyDome, the two icons had never before clashed in a one-on-one encounter on WWE television. When Ric Flair’s interference with a lead pipe allowed The Rock to defeat The Undertaker at No Way Out, it gave the two ring titans an excuse to clash on The Grandest Stage of Them All, not that they needed one.

Due to The Deadman attacking Flair’s close friends and family on the road to The Show of Shows, the contest was deemed a No Disqualification Match. Each competitor’s signature maneuvers were well scouted and the two veterans showed their prowess with a series of reversals. The wild brawl had moments outside the ring and the Charlotte, N.C., native was busted open in what became a truly brutal fight. Arn Anderson inserted himself into the action, nailing a patented spinebuster on The Phenom. But despite The Enforcer's involvement, it was a familiar sight as The Undertaker pinned Flair after a Tombstone Piledriver to extend The Streak to 10-0. ( WATCH)

Undertaker and The Nature Boy clashed again in a tag team match on Raw four months later, but never again on television in singles competition.

( MORE UNDERTAKER | MORE FLAIR)

WWE Champion “Macho Man” Randy Savage vs. Shawn Michaels: European Rampage Tour 1992

In 1989, 1990 and 1992, Randy Savage and Shawn Michaels both competed in the 30-Man Royal Rumble Match, but they never met on television in singles competition until WWE landed across the pond in the early 1990s. Soon after “Macho Man” defeated Ric Flair for the WWE Championship at WrestleMania VIII, WWE staged a European Live Event tour where Savage competed in some of his first title defenses.

On April 19, 1992, WWE held a pay-per-view from Sheffield Arena (now Motorpoint Arena Sheffield) only available in Britain called UK Rampage. The event featured Michaels, recently minted as The Heartbreak Kid, in his first opportunity to challenge for the WWE Championship against Savage. Though the match has rarely been seen by American audiences, the contest has been regarded as one of the bouts that established HBK as a bona fide singles star. The legends shared many parallels. Each man owned one of the greatest top rope elbow drops in ring history. And Sensational Sherri, who accompanied Michaels to the ring for the match, was formerly aligned with her “Macho King.” HBK controlled much of the contest in a highly impressive performance, but Savage retained the title after a thrilling exchange of near-falls and a crossbody off the ropes. ( WATCH)

Savage had already solidified himself as a household name, but Shawn had yet to become the revered icon that he is today. They later each competed in the 1994 Royal Rumble Match, but never again in a singles bout. We sure wish they would have.

( MORE "MACHO MAN" |  MORE SHAWN MICHAELS)

Ultimate Warrior vs. Triple H: WrestleMania XII

A minute and a half. That’s all it took for the returning Ultimate Warrior to defeat a very young Triple H at WrestleMania XII. ( WATCH) Long before he was the eight-time WWE Champion who took the unstoppable Brock Lesnar to the limit in “The Perfect Storm” at SummerSlam 2012, the future Cerebral Assassin couldn't last 120 seconds against the highly polarizing Warrior. The same Game who manhandled The Undertaker and nearly ended The Streak in an End of an Era war at WrestleMania XXVIII succumbed to a gorilla press drop and running splash after a only a few offensive maneuvers.

( MORE WARRIOR | MORE TRIPLE H)

WWE Champion John Cena vs. Mr. McMahon: Raw, March 27, 2006

When Mr. McMahon battled CM Punk on Raw, it was far from the first time that The Chairman battled his company's champion. ( WATCH MR. MCMAHON'S BEST MATCHES) In 2006, on a roll from appearing on the cover of Muscle & Fitness magazine and preparing for his WrestleMania 22 clash with Shawn Michaels, Mr. McMahon “punished” John Cena by forcing the young Superstar to face The Boss in the main event on Raw one week before The Show of Shows.

The encounter didn't last long. The two combatants locked horns in a test of strength, with Mr. McMahon going pound for pound with Cena, forcing The Champ to struggle. The Chairman even managed to capture Cena in a prolonged headlock. But after Cena gained the upper hand, his enormous boss had enough and nailed Cena with a blatant low blow for the disqualification. ( WATCH) HBK and Cena's WrestleMania foe, Triple H, had been watching the match while handcuffed to the ropes at ringside, but Mr. McMahon unlocked The Game and the two proceeded to assault their upcoming Show of Shows opponents.

Fours year later, The Chairman once again battled Cena. But this time he had the help of Vladimir Kozlov, Drew McIntyre, Jack Swagger and Mark Henry in a 5-on-1 Handicap Gauntlet Match. But judging from his recent match against Punk, Mr. McMahon clearly doesn't need the help if he were to ever battle Cena one-on-one again.

( MORE MR. MCMAHON | MORE CENA)

“Stone Cold” Steve Austin vs. Mr. Perfect: Raw, Feb. 25, 2002

By the time “Stone Cold” Steve Austin arrived in WWE in 1995, Mr. Perfect was no longer an active in-ring competitor and soon departed the organization to try his hand in WCW. Choosing to compete as Curt Hennig, he was a member of the legendary Four Horsemen and influential nWo groups while “Stone Cold” rose to superstardom on Raw.

Following WWE's acquisition of WCW, Mr. Perfect returned to WWE as a surprise entrant in the 2002 Royal Rumble Match. His homecoming was spoiled by The Texas Rattlesnake, who nailed the former Intercontinental Champion with a steel chair. The following night on Raw, Austin did the same thing during Mr. Perfect's match against Val Venis. One month later, Mr. Perfect had an opportunity to achieve retribution. These two WWE Hall of Famers had never before met in a match, and while Austin was mostly known for his brawling style, he could go toe-to-toe with the technical fundamentals of Mr. Perfect. ( WATCH)

( MORE MR. PERFECT | MORE "STONE COLD")

Bret & Owen Hart vs. The Steiner Brothers: Wrestlefest ’94

In a different kind of sibling rivalry, two sets of brothers (and four great wrestlers) battled each other in a match never shown on television in America during a WWE event in January 1994. Bret and Owen Hart, only months before their classic clash at WrestleMania X, joined forces to face off with The Steiner Brothers. ( WATCH)

The match was a clinic in tag team wrestling and ended without a conclusive victor. After nearly a half hour of action, the referee called for the bell when Owen and Scott Steiner leaped onto their opponents who were battling on the floor. The double count-out officially ended the contest, but the four technicians brawled at ringside until being separated by WWE personnel. Scott demanded the match continue, but he and Rick Steiner changed their minds much to Bret's dismay. The brothers all began to fight once again, and were again separated by officials and locker room producers. After the competitors cooled down, the Superstars hugged and shook hands in the ultimate display of respect.

( MORE BRET HART | MORE SCOTT STEINER)

Goldberg vs. Brock Lesnar: WrestleMania XX

It is one of the most controversial matches in WWE history. Two titans of the ring known for their long undefeated streaks finally met in a highly anticipated clash at WrestleMania XX in Madison Square Garden. And to make sure these two warriors didn't take out the front row, “Stone Cold” Steve Austin was assigned to be the special referee. But on this night, perhaps the renowned building should have been referred to as The World's Most Infamous Arena.

It had been known for quite some time that this would likely be Goldberg's final match in WWE. But one week before The Show of Shows, rumors began to surface that Lesnar, too, would be departing WWE. When the two finally met face to face in the ring, the knowledgeable New York City fans weren’t interested in seeing these two dominant competitors and jeered the Superstars they perceived as quitters. After both Lesnar and Goldberg traded their signature maneuvers, it was Goldberg who picked up the victory. But the only cheering inside MSG was for The Texas Rattlesnake, who dropped each powerhouse with a “Stone Cold” Stunner. ( WATCH THE MATCH | WATCH THE STUNNERS)

Goldberg never returned to WWE, and Lesnar once again quit the organization after defeating Triple H in 2012, leaving the WWE Universe with so many “woulda, coulda, shouldas.”

( MORE GOLDBERG | MORE LESNAR)