Novak Djokovic moved into the semi-finals of the French Open on Monday as his quarterfinal opponent Fabio Fognini had to withdraw from their Tuesday match on doctors’ orders due to a leg injury.

Djokovic, whose winning streak of 41 straight matches cannot be improved by the walkover, still stands one win away from levelling the all-time best of 42 straight from the start of a season set by John McEnroe in 1984.

The Serb won his 41st of 2011 on Sunday as he beat Frenchman Richard Gasquet in straight sets.

“I had another scan this morning and I have a little problem with my leg,” said the Italian who won a four-hour-plus battle against Albert Montanes and was treated controversially for cramping as he booked into the last eight. “I’m having the best tournament of my career, so it’s tough to pull out.

“The doctors say if a play tomorrow, it maybe it could be dangerous, so I decided to retire. It was a really difficult decision.

“I’m in the quarterfinals in Paris playing against Djokovic. But I think this is the best solution.” Djokovic will have had four days off by the time he faces a semifinal opponent.

Nadal through to last eight

Defending champion Rafael Nadal defeated Ivan Ljubicic 7-5, 6-3, 6-3 to reach the quarterfinals of the French Open on Monday, extending his record at Roland Garros to 42-1.

Nadal is trying to equal Bjorn Borg’s record of six titles at the clay-court tournament this year and will next take on either two-time runner-up Robin Soderling or Gilles Simon.

The top-ranked Spaniard lost to Soderling in the fourth round two years ago and defeated him in last year’s final.

Nadal needed five sets to beat John Isner in the first round but didn’t lose a set in his next three matches.

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