After three consecutive tournament exits against low-ranked opponents, Roger Federer pulled out of next week's Rogers Cup without giving a reason Friday.
The owner of a record 17 Grand Slam titles did recently complain about a bad back, however.
Federer, who turns 32 next Thursday, made the unusual move of participating in a pair of minor clay-court tournaments in the period between playing on Wimbledon's grass and shifting to the North American summer hard-court season.
A loss to 116th-ranked Sergiy Stakhovsky in the second round at the All England Club ended Federer's streak of reaching the quarterfinals at 36 consecutive major tournaments. It also marked Federer's earliest Grand Slam exit since 2003.
Next came a semifinal loss on clay at Hamburg to 114th-ranked qualifier Federico Delbonis, followed by a defeat against 55th-ranked Daniel Brands in Federer's opening match on clay at Gstaad, Switzerland. In addition to his bothersome back, a recurring issue, Federer was experimenting with a new, larger racket at those tournaments.
Still, those results are not the sort Federer usually produces. This has been a tough season by his standards: He is 30-10 with one title in 2013. After Wimbledon, Federer tumbled to No. 5 in the ATP rankings, the first time in a decade he's been that low.
Missing Montreal limits his hard-court preparation for the U.S. Open, the year's last Grand Slam tournament, which begins Aug. 26.
"I am disappointed not to be playing in Montreal next week," Federer said in a statement released by the tournament, which starts Monday. "It is a great tournament with amazing fans. I look forward to competing there in the future."
He won the Rogers Cup when it was played in Toronto in 2004 and 2006. Federer lost to Novak Djokovic in the 2007 final at Montreal.
Federer's withdrawal diminishes a Montreal field that already was missing No. 8 Jo-Wilfried Tsonga and former top-10 player Mardy Fish.
In addition, the tournament announced Friday that Viktor Troicki and Marin Cilic won't compete. Troicki was recently suspended for 18 months by the International Tennis Federation for failing to provide blood for a drug test. He is appealing that ruling. Cilic pulled out of Wimbledon, citing an injury; he reportedly is facing a doping suspension, but the ITF has not confirmed or denied whether that is true.
Ivan Dodig of Croatia and Pablo Andujar of Spain were added to the Montreal field.