WIMBLEDON, England—On Wednesday, Sergiy Stakhovsky did something no one expected: He became the first man in nine years to beat Roger Federer before the quarterfinals at a Grand Slam.

In the men’s draw, Ukrainian Sergiy Stakhovsky won his second tournament of the year, beating Denis Istomin of Uzbekistan 3-6, 6-3, 6-4. Stakhovsky is unbeaten in four career ATP finals ...