Flair and Undertaker faced off in a brutal No Disqualification Match at the SkyDome in Toronto, Ontario, Canada.
Even though The Deadman won and extended his legendary WrestleMania undefeated streak, The Nature Boy proved he had what it takes to perform at the Grandest Stage of Them All despite his advanced age of 53.
The 16-time world champion had just rejoined WWE after WCW went out of business and his confidence was very low.
However, Flair returned to his old self after Mania and went on to wrestle for another six years.
The ex-WWE Champion said during an episode of WWE Photo Shoot: “WrestleMania 18, Toronto. That looked like it was rough but that was one of my greatest nights of my career.
“He single-handedly helped restore my self-confidence, which was totally gone.
“At that point in time, I was 55 [53] years old, and just didn’t see myself back in the ring.
“Mark [Calaway, Undertaker’s real name] really got me up and running. We had a hell of a match.”
Undertaker and Flair never faced each other again after that WrestleMania barn burner as The Deadman went to Smackdown and The Nature boy stayed on RAW.
Once the WCW legend found his lost confidence he went on to have some unforgettable matches against the likes of Triple H and Edge.
But Flair’s greatest ever bout during his second WWE run took place at WrestleMania 24 in his last ever fight against Shawn Michaels.
Michaels beat the WWE Hall of Famer with Sweet Chin Music in a Career Threatening Match and retired the wrestling legend.
Undertaker is now of the exact same age Flair was during their WrestleMania 18 match and still wrestles in Vince McMahon’s promotion on a part-time basis.
The seven-time world champion hinted at retirement last year at WrestleMania 33 after losing an emotional bout to Roman Reigns as he broke character and placed his signature black jacket, gloves and hat in the middle of the ring before saluting the crowd.
But the ex-WWE Champion returned a year later at WrestleMania 34 and destroyed John Cena in less than three minutes in an impromptu match.
The Phenom then annihilated Rusev at the Greatest Royal Rumble in a Casket Match and then returned to Madison Square Garden where he teamed up with Braun Strowman as well as Reigns and beat Kevin Owens, Baron Corbin and Elias in a Six Man Tag Team Match.
Undertaker is now set to take on Triple H for the last time ever at WWE Super Show-Down on October 6 at the Melbourne Cricket Ground in Australia and hinted at another battle with Michaels.