John Isner will likely be knocked out of the U.S. Open after he was diagnosed with ligament damage in his ankle, per Judy Murray (via the Tennis Reporters). Isner admitted as much over his own Twitter account, saying:
Ankle is worse than I thought. Need a miracle
Isner injured the ankle during his match against the resurgent David Nalbandian at the Cincinnati Masters last week. Isner was up 5-4 in the first set, serving for the set, when he landed awkwardly and twisting his right ankle. Isner was forced to retire from the match. Although Isner was initially hopeful that the injury would be similar to the one he suffered to his ankle last year that didn't knock him out for very long, that does not appear to be the case now.
The hard-serving Isner is, of course, best known for his epic, marathon match against Nicolas Mahut at Wimbledon this past July. The six-foot-nine Isner eventually prevailed 70-68 in the fifth set, due to there not being a fifth-set tiebreak at the All-England Club.