KEI Nishikori, the No 5 seed and last year's US Open runner-up, has withdrawn from this year's tournament with a calf injury.

The Japanese player has been suffering from the problem ever since the recent grass court event in Halle and while he made it past Simone Bolelli of Italy in five sets in the first round here, he succumbed to the problem on Wednesday. His absence hands opponent Santiago Giraldo a walkover in the next round.

"It is same injury," said Nishikori. "It got better before the first match and I thought it was really going to be okay. But last match in fifth set I was hurting too much. It was hurting when I was just walking and running, so I decide not to play. It's not a big injury, just a little tear."