Arsenal manager Arsene Wenger believes defeat for either France or England in next week's Group D clash could spell the end of their Euro 2012 hopes.
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England face in-form France in Donetsk on Monday in a match Wenger believes will be pivotal in deciding the outcome of the group, which also includes Sweden and hosts Ukraine.
Wenger said in an interview on Arsenal's official website (www.arsenal.com) that England could face an uphill struggle in the absence of the suspended Wayne Rooney, who misses the Three Lions' opening two games.
"The opening game is England v France and there is no Rooney. You would say that is a game that you can not afford to lose," Wenger said.
"Why? Not because you cannot catch up, but (because) the pressure inside the country becomes tremendous straight away.
"That game could dictate the whole group. If it's a 0-0 draw, the group is all open, but if someone loses they have a very good chance of going out because Ukraine will beat one of the two, you would say, and Sweden are a hard team to beat."
Wenger believes England's opener will determine whether the team can thrive following the 11th-hour appointment of Roy Hodgson as manager last month.
"England have no Rooney, they have a new manager and they have not worked together so... it's a quick fix," he said.
"Can it work or not? The first game will be a good indication.
"England do have an advantage as Hodgson has managed national teams before, has good experience of tournaments and knows the English players well. It's not unknown territory (for him).
"At the moment England struggle to find confidence and unity and if he can manage to do that he can do very well."
Meanwhile Wenger believes France has the ability - and the players - to repeat their Euro 2000 triumph though he fears that the memories of their 2010 World Cup debacle, when it reached its nadir with a players strike, still linger.
"France has the players to win this tournament," Wenger said.
"But they have not got the confidence and have no certainty.
"South Africa is still inside the team a little bit. Expectation levels in France are low because the scars are still there, but they have the quality.
"They have Benzema, (Franck) Ribery, (Samir) Nasri.
"If they can gel well and they can be psychologically comfortable, they can be a surprise at this tournament."