Rafael Nadal's coach and uncle Toni has insisted that the Spaniard's knee injury is not a cause for concern.

The 27-year-old only returned in January following several months on the sidelines with tendinitis. He went on to win the French Open, but on Monday he appeared to be in a lot of pain as he lost out in the opening round of Wimbledon to Steve Darcis.

However, his mentor has hinted that a poor performance rather than the injury was behind the world number five's exit.

"In the sport you can win and lose. Many times you lose. The knee injury is not a worry. His knees were the same here as Roland Garros and he won the tournament there," Toni told BBC Sport.

"It is impossible not to play Wimbledon. Losing in the first round is bad but not playing is so much worse. We will come back every year here and we like so much to come here. I'm sure next year we will play better here."

A year earlier Nadal was defeated in the second round at Wimbledon by Lukas Rosol.