LONDON -- It has been a day of upsets and injuries at Wimbledon. Seven-time men's champion Roger Federer was stunned by 116th-ranked Sergiy Stakhovsky in the second round, losing the match 6-7, 7-6, 7-5, 7-6.
It's Federer's earliest loss in a Grand Slam tournament in a decade.
On the women's side, Maria Sharapova was ousted by a 131st-ranked qualifier. The third-seed and 2004 Wimbledon champion was beaten by Michelle Larcher de Brito of Portugal, 6-3, 6-4.
Sharapova slipped and fell several times on the grass on Court 2 and received medical treatment from the trainer in the second set. No less than seven singles players withdrew or retired because of injury.
Leading the group were American John Isner and women's second-seed Victoria Azarenka. Isner retired during his second-round match against Adrian Mannarino of France with a left knee injury after only two games.
Azarenka withdrew minutes before her second-round match against Flavia Pennetta after being injured in her first round match.
Steve Darcis, who registered one of Wimbledon's greatest upsets Monday when he beat two-time champion Rafael Nadal in straight sets, had to pull out of his second round match with an injured right shoulder.
And men's No. 6 Jo-Wilfried Tsonga stopped playing while trailing Ernests Gulbis two sets to one after having his left leg treated by a trainer.
In men's results, second-ranked Andy Murray advanced to the third round, while former champion Lleyton Hewitt lost to German qualifier Dustin Brown.
Hewitt, who upset 11th-seeded Stanislas Wawrinka in the first round, was overwhelmed by Brown, losing 6-4, 6-4, 6-7, 6-2. For the women, American Sloane Stephens was a winner.
The 17th seed beat a German and moved onto the third round while former world No. 1 Caroline Wozniacki slumped to a 6-2, 6-2 defeat to Petra Cetkovska in their second round match.
The ninth-seeded Wozniacki, who has never fared very well on the London grass, also lost in the 2nd round at the French Open.