Although UFC 137 was a lack lustre event, with a number of fights going to the decision, and GSP unable to complete due to injury, it will be remembered as the event at which two legendary fighters hung up their gloves.

UFC 137 marked the retirement of legendary striker Cro Cop, and MMA protege BJ Penn. Although Cro Cop's never technically announced retirement after his 3rd round loss to Roy "Big Country" Nelson, he thanked his fans and the UFC for the support over the years and expressed his disappointment in not being able to go out on a win. Given it was the last fight on the Croatian Striker's contract, it seemed only appropriate that this was his swan song. 

BJ Penn on the other hand appeared to surprise Joe Rogan with the announcement of his retirement, stating that he didn't want to go home "looking like this" to his children. Penn was convincingly beaten by the rangier fighter Nick Diaz, yet even though looking gassed half way through the second still managed to come out in the 3rd and trade.

The world of mixed martial arts is greatful for the contributions of these two fighters. Cro Cop will surely go down with one of the best highlight reals of spectacular knockouts, and BJ penn with his freakish rubberguard and dynamic fighting style.