Robert Pires will be out for up to nine months because of what Arsenal described yesterday as "serious cruciate knee-ligament damage". The injury has dealt a major blow to the club's quest for the double, though its impact will be felt far beyond Highbury.

While Arsenal contemplated losing the Premiership's outstanding performer until next season, France swallowed the news that one of their key men can play no part in their quest to retain the World Cup. The national coach, Roger Lemerre, blamed Pires's gruelling schedule of games.

Club, country and Pires himself have been cruelly hit by the injury, which occurred during Arsenal's FA Cup victory over Newcastle on Saturday. After that match the midfielder talked of being back after a few games and said he was "not too worried".

His manager, Arsene Wenger, said surgery seemed unlikely. Within 48 hours their optimism was shattered.

Pires was examined in Paris by the specialist Philippe Boixel, who has also treated Steven Gerrard and Christian Vieri, among others, and will undergo surgery after it became apparent he had ruptured anterior cruciate ligaments. It is hoped one operation will suffice. The ligament will be replaced with tendons taken from elsewhere in his body, probably from a hamstring or other muscles in his knee.

Arsenal said the 29-year-old would be out for "several months" and wished him a "full recovery". Pires damaged his right knee when he fell awkwardly trying to hurdle a challenge by Newcastle's Nikos Dabizas. By then he had put Arsenal on their way by scoring his 13th goal of the season.

No one at Manchester United or Liverpool will celebrate such an injury, but they know their title chances have been strengthened.

Pires has played 80 times for Arsenal and France in the past 18 months and said fatigue had played a part in his failure to adjust his leg when he jumped over Dabizas.

"I feel this injury is down to tiredness," he said. "In general those type of jumps I'm very careful with. When my foot touched the ground my knee twisted and I immediately wanted to pull it back. That's when I heard it crack. In my head I felt weak at this very moment. I was not paying full attention. If you add some tiredness to this, it was just enough for my knee to twist.

"Obviously it's tough, as every player wants to play in (the World Cup), but I'm not going to cry over myself. That's life and I'd better be philosophical about it. So far I've been spared from injuries. I'll be back soon, stronger than ever."

Lemerre was quick to pick up the tiredness theme. "We know the players who are playing loads of games during the season become very fragile and we think Pires's injury is due to the accumulation of games.

"Pires and (Thierry) Henry are the two players who have played the most this season. They have played around 45 or 47 games. After a certain limit, it becomes very dangerous. They play at a very high level. The competition and the pressures are very high and it can have serious consequences on their health," he said.

Pires performances have made him a strong contender for player of the year. He has been arguably the most influential figure in Arsenal's push for the double with his speed, vision and much-improved goalscoring. His sublime strike at Aston Villa symbolised his season.

His distinctive, scuttling runs have made him equally indispensable to France and he would have assumed a key role at the World Cup. He has featured in almost all his country's matches since coming off the bench to help them win Euro 2000 and Lemerre described him yesterday as "one of our best elements".

"I think it will affect the whole of France," Lemerre said. "It is sad news for the world of sport."