Johnson stuns Isner in quarter-finals

Fifth seed Steve Johnson produced a big upset at the Citi Open on Friday as he defeated top seed John Isner 7-6 (7), 7-6 (15). 

Isner will be disappointed not to have reached the semi-finals as it the first time he had progressed to the last eight of a tournament since the US Men’s Clay Court Championships in April.

Johnson will face Ivo Karlovic in the semi-finals after the 13th seed downed sixth seed Jack Sock 7-6 (4), 7-6 (6).

Meanwhile, second seed Gael Monfils also made it to the semi-finals after beating eighth seed Sam Querrey 6-4, 3-6, 6-1. Monfils will go up against seventh seed Alexander Zverev after he cruised past fourth seed Benoit Paire 6-1, 6-3.