He's trying to get past Nicolas Mahut and clear the first round at Wimbledon for the first time in his career.
Update: This is just ridiculous. They've suspended play again. From The New York Times:
On Wednesday, it resumed, but after 118 games in the fifth set, which itself would be the longest match in Wimbledon history, the sun set and play had to be suspended again.You can watch the tape delay now (4:50 p.m. eastern) on ESPN2. According to the broadcast, Isner has smashed the world record for aces in a match, recording more than 90.
Thursday update: Our man John Isner has won. Damn good dawg.