By Chris Harris

Arsène Wenger is "devastated" to see Tomas Rosicky back on the treatment table.

The Czech midfielder was substituted at half-time on Saturday after suffering a groin injury in the first half of Arsenal's 2-0 victory over Stoke City.

Depending on the severity of his injury, Rosicky could be out for three weeks. To make matters worse, Wenger admitted afterwards that he had gambled - and lost - on the 29-year-old's fitness ahead of the weekend fixture.

"Tomas is devastated and I am as well," said the manager.

"Before today I thought 'he has played the whole game Wednesday night [at Manchester City], do I take the gamble or not?' Because it was such an important game I took the gamble and at half-time it backfired so it is very disappointing.

"The first impression is that it will not be long term. It is a groin problem and we have to see with the scan whether it is grade one, grade two or grade three. If it is grade one it is 10 days, if it is grade three it is three weeks at least. At the moment I cannot tell you."

This latest setback is particularly harsh on Rosicky after he recently returned from an 18-month lay-off. The Czech international is one of 12 names on Arsenal's current injury list, a figure which prompted one journalist to ask whether Wenger had faith in his medical staff. The Frenchman was unequivocal in his reply.

"Our medical team is very good," he insisted.

"I think it is a vicious circle when you have been out for a long time, like Eduardo has for example. He had not played for 18 months, Tomas had not played for 18 months, then you come back and suddenly your body has to get used to producing the energy level and at that level, to repeat the games, it is difficult and nobody masters that enough."

Copyright 2014 The Arsenal Football Club plc. Permission to use quotations from this article is granted subject to appropriate credit being given to www.arsenal.com as the source 7 Dec 2009