Novak Djokovic joins Rafael Nadal on the sidelines at Qatar Open

Karlovic coped the better with the windy conditions to secure a 6-7 7-6 6-4 victory to reach the semifinals, a surprise even to the 35-year-old who described it as “unbelievable” in his post-match interview.

“When I arrived here, I didn’t expect that one. He wasn’t able to show his full range because it was windy. I just focused on my game and in the end I was a little luckier.”

Federer lost the first set of the second round match before rallying to a 4-6 6-4 6-3 victory.

CNN