Michael Chang
When he won the French Open in 1989, Chang had a well known semi-final match with Ivan Lendl.  Before the match, many people thought the unseeded Chang would lose to the No. 1 ranked Lendl.  At first Chang was losing, but he won the important third set.  Starting then, Chang began to have leg cramps, but won the match through determination.  Today, many people remember this game as one of his best matches when the name Michael Chang is mentioned.