#1 Triple H (c) vs Randy Orton - WWE Championship (WrestleMania XXV)

Randy Orton's return in late 2008 came with a whole new persona for the Legend Killer, who was now more vicious and mentally unstable than he had ever been in his entire career. Engaging in a storyline with the McMahon family, Orton somewhat Loose Cannon character turned him into the most hated superstar in the entire world.
In fact, his act of attacking Vince McMahon, Shane McMahon and, more importantly, Stephanie McMahon caused Triple H to intervene. This began a heated feud between the two that had Orton kiss an unconscious Stephanie in front of a handcuffed HHH and The Game returning the favour by attacking Orton in his house and sending him through the glass window.
All these signs pointed to a brutal fight between the two at Mania XXV, or as everyone but WWE had thought. WWE's mind boggling stipulation of Triple H losing his title if he got himself disqualified was one of the biggest reasons for this match's downfall, as this took out all the hardcore wrestling out of the picture.
Fans had to sit for over 25 minutes, watching Orton and HHH wrestle a slow plodding match. This was also at the end of a show which had Shawn Michaels and Undertaker wrestle the best match of all time merely an hour ago.
What's even more horrible is the fact that Orton lost the match fair and square inside the ring, and had to wait for one more month to win the match. Triple H and Randy Orton had the potential to wrestle one of the greatest main events of Mania, but all they did was end up being part of one of the worst of all time.