RIO DE JANEIRO (AP) — Two-time major champion Stan Wawrinka pulled out of the Olympics on Tuesday because of injury, leaving the Rio Games without half of the men ranked in the ATP's top 10.

A statement issued by Wawrinka's management company said he "felt increasing pain" during the Rogers Cup in Toronto last week and was told by his doctor after an MRI exam to "reduce his physical activity for an undetermined period."

The statement does not say where Wawrinka is injured. He lost in the semifinals in Toronto.

Wawrinka, who is No. 4 this week, joins his Swiss teammate Roger Federer, who is No. 3, along with No. 7 Milos Raonic of Canada, No. 8 Tomas Berdych of the Czech Republic and No. 10 Dominic Thiem of Austria in withdrawing from the Rio de Janeiro Olympics for a variety of reasons.

No. 5 Rafael Nadal has been sidelined with an injured left wrist since the French Open and has been testing his fitness in Brazil.

The draw for tennis in Rio is Thursday. Play begins Saturday.

Wawrinka won the 2014 Australian Open and the 2015 French Open.

He teamed with Federer to win a doubles gold medal for Switzerland at the Beijing Olympics in 2008.

Another Swiss tennis player, Belinda Bencic, also pulled out of Rio.