The second seed advanced to the Round of 16 in New York for the 15th consecutive year, extending his FedEx ATP Head2Head series to a perfect 10-0 against the German. Federer fired 27 winners including five aces, while converting on five of eight break chances.
He conceded his first break of serve since Wimbledon, when Kohlschreiber broke to love in the fourth game of the second set. Federer had held in 78 consecutive service games in Cincinnati and the US Open combined. He improved to 19-0 against Germans at Grand Slams since falling to Tommy Haas at the 2002 Australian Open, and is just six match wins from becoming the first player to claim 300 Grand Slam victories (294-48).
The Swiss continues his bid for a sixth title at Flushing Meadows when he tangles with John Isner in Monday's fourth round. No. 13 seed Isner advanced when Jiri Vesely retired down 6-3, 6-4 with a neck injury. The top American hammered 21 aces and 46 winners.
Federer owns a 4-1 advantage against Isner, but this will be their first encounter since the 2012 Summer Olympics. The second seed won their most recent hard-court meeting in the '12 Indian Wells final, while Isner's lone victory came on clay in the Davis Cup first round earlier that year.
Isner will hope to notch his seventh Top 5 win and equal his best result at his home Grand Slam, having previously advanced to the quarter-finals in 2011 (l. to Murray).
Sad to see that serving streak end.
It was mostly due to Roger's sloppiness & poor serving more then anything else in this match.
He'll have to serve 50% better against Isner next.