WASHINGTON -- Japan's Kei Nishikori has withdrawn from next week's hard-court tournament in Toronto because of what his agent says is a "severely infected right big toe."

Nishikori's agent, Olivier Van Lindonk, says Sunday that Nishikori has been struggling for a week with the problem and most likely will need "a small procedure to remove the infection."

Nishikori lost to Richard Gasquet in the quarterfinals in Washington on Friday. Gasquet said he could tell his opponent was injured, but Nishikori said after the match he was fine.

Nishikori, the first Japanese man to reach the top 10 in the rankings, is No. 11 this week.

Missing the Rogers Cup in Toronto deals a blow to Nishikori's preparation for the US Open, which begins Aug. 25.