#2 The Rock and Chris Jericho

At SummerSlam 2001, The Rock defeated Booker T to become the WCW Champion and held the title for 63 days before losing the title to Chris Jericho, Y2J's very first World title in the company.
One night later, on Raw, both The Rock and Jericho teamed up to face The Dudley Boyz for the World Tag Team Championship, having supposedly put their differences aside. Both men were part of WWE against the invading forces of WCW and ECW and so decided to put their personal problems to one side to come together for the sake of their company.
The Rock and Jericho were successful in their quest, defeating The Dudleys to win the gold. However, this would be rather short-lived as, just eight days later, Rock and Jericho lost the belts to Booker T and Test on an episode of SmackDown, reigniting their hatred for one another.
This is a short, oft-forgotten reign, but part of much bigger storyline that eventually saw Chris Jericho become the first-ever Undisputed Champion at the end of 2001, beating The Rock and Steve Austin on the same night.