Arsène Wenger was given the news in Paris on Wednesday night, after he had watched France's 2-0 win over Holland in his capacity as a TV pundit. Jack Wilshere, the Arsenal manager was told, had taken a heavy tackle during England's 1-0 victory over Denmark but there was no reason to worry. It was nothing serious. Wenger should have known better.

"The problem of Jack," Wenger said on Friday morning, as he drew upon lengthy and frustrating experience, "is that he is a bit less sensitive, he has a high pain threshold. That is why he is in danger sometimes because he doesn't feel pain. He just goes on and, after, you see a disaster has happened.

"I wonder as well, [how] has he done that fracture at the moment [in the 12th minute] and was capable to play the whole game before he went off [on 59 minutes]? I don't understand how he could do that.

"So many times, I sit there and say to the physio: 'Come on, how bad is it?' And I'm told that Jack says he wants two or three minutes and, after that, he continues to play. You think you have to take him off straight away on a stretcher and, after that, suddenly, he can go on. He is very, very, very resistant to pain."

Everybody now knows that Wilshere suffered a hairline fracture to the top of his left foot in the 12th-minute challenge with Daniel Agger, the Liverpool and Denmark defender and, according to Wenger, the Arsenal midfielder will need six weeks of rehabilitation and two more after that to regain match fitness.

If everything goes to plan, Wilshere will be back on 3 May for the penultimate round of Premier League fixtures and in time to be included in Roy Hodgson's squad for the World Cup finals, which the England manager will name on 13 May.

Wenger said he was certain that Wilshere would be 100% fit for Brazil and although he reported that the player was "very down" and had gone away for a short break in order to get a bit of "space", the manager himself was pragmatic.

He said that Agger had "wanted to go for the ball", that the injury was an "accident" and he did not blame the England medics for allowing Wilshere to continue. He also took issue with those who have questioned both Wilshere's wisdom in jumping into the challenge and his subsequent refusal to come off, following the initial surge of pain. The 22-year-old's courage has somehow been used to condemn him, which is pretty ironic given the general desire in this country for England players to have the hearts of lions.

"We are always sitting here saying – and you writing – that you want full commitment from the players and so when you get it, you don't want to say he shouldn't commit," Wenger said. "When Jack was younger I told him not to go into stupid challenges. He has improved a lot on that front. He went in the other night. Did he need to go in there? You always point to your instinct in that situation."

The bottom line, however, is that Arsenal have been left to pick up the pieces after the international break. Wenger did not see Laurent Koscielny in action for France against Holland because the defender had a hamstring problem – he faces a fitness test ahead of Saturday's FA Cup quarter-final at home to Everton – while Mesut Özil, below, whose confidence has been at a low ebb, was jeered by Germany fans upon his substitution towards the end of the 1-0 win over Chile.

"I am quite surprised that that happened," Wenger said. "I haven't spoken to Mesut about it yet. But if he feels physically all right, I will start him [against Everton]."

Wenger's bad luck has not been restricted to threes. Aaron Ramsey, out since Boxing Day with a thigh strain, might have returned to full training on Monday but he remains a week away from fitness while Kim Kallstrom, the January loan signing who has carried a back injury, is on a similar recovery timetable.

It does not get any easier for Wenger as he chases a first trophy since 2005 and Everton's visit comes on the back of last Saturday's 1-0 defeat at Stoke City, which saw Arsenal slip four points off the title pace. They are 2-0 down to Bayern Munich going into Tuesday's Champions League last-16 second leg in Germany and it is possible to see the FA Cup as the club's best chance of a trophy. Everton, though, are a tough nut to crack, as they proved when they drew 1-1 at the Emirates in the league last December.

Wenger has given the impression in seasons gone by that the FA Cup lags some way behind the Premier League and the Champions League in terms of importance, but you suspect he would give almost anything to win it this time round.

"For us it's vital because we had such a disappointing result at Stoke and a non-convincing performance offensively," Wenger said. "We need a great response. What we produced last week was not good enough. How important is it to win a trophy this season? It's vital."