The news of the severity of Theo Walcott's injury came as a dreadful shock. As he left the field on a stretcher during Arsenal 's FA Cup victory over Tottenham Hotspur on Saturday, he responded to missiles thrown Tottenham fans by showing them the score with his fingers: 2-0 . That was not the gesture of a man who had just ruptured an anterior cruciate ligament. Nobody at that moment had any inkling that he might be out for any more than a couple of weeks. Nobody dreamt that he would be out for the season, that one slightly awkward challenge could have ended his hopes of going to the World Cup .

Walcott was an oddity of the 2006 tournament, selected at 17 by Sven-Goran Eriksson, who later admitted he had never seen him play, and then didn't give him a single minute of action during the tournament. Fabio Capello didn't pick him four years later and now he won't be going to Brazil. Walcott is still young enough to dream of 2018 and 2022 but the possibility has just grown stronger that his only World Cup experience will be looking lost in Germany, his father sitting alone in the only curry house in Baden Baden, bewildered as the full circus of Eriksson's WAG-rich regime played out in front of him. For a player who has always been one of the quieter, friendlier members of the England squad, it all seems desperately cruel.

It's a terrible blow too, of course, to England and to Arsenal, for both of whom Walcott's pace is a major weapon. Even if he is playing badly, or if his team is under pressure, the fact that Walcott can burn away from opponents means he is always in the back of defenders' minds; they can't push forward with abandon. Given Roy Hodgson had suggested he would set England up at the World Cup to defend and spring forward on the break, the loss of Walcott -- even if he was only intended as an impact substitute -- may force something of a rethink. For Arsenal, the tactical issues are more immediate.

Video: Arsenal v Tottenham FA Cup Full Game Highlights 01/04/13

In a sense, and it sounds callous to say it, if Arsenal had to lose a player from any position on the field, it would be from that line of three attacking midfielders, the one area of the squad in which they have depth. Walcott didn't play between mid-September and mid-November and although Arsenal did lose three times in that spell -- to Borussia Dortmund in the Champions League , away at Manchester United in the league and, with a much-changed side, to Chelsea in the Capital One League Cup -- it couldn't be said his absence caused the general level obviously to drop.

The match against West Ham in December, though, showed Walcott's value as he scored twice late on in a 3-1 win , his darting runs -- far more considered now than when Chris Waddle accused him of lacking "football intelligence" four years ago -- unpicking a defense that had threatened to frustrate Arsenal. He also offers genuine width, something Arsenal can lack if Walcott's position on the right is taken, as it has been at various points this season by Aaron Ramsey -- who is recovering from a thigh injury, Jack Wilshere -- who has an ankle problem that means he can't be overworked or Tomas Rosicky. That is less of an issue for Arsenal than it can be for some sides, their technical ability allowing them to avoid the sense of congestion that could overwhelm other sides who played that narrow, but the ability to alter the angle of attacks remains important.

The Club regrettably announces Theo Walcott has been ruled out for at least six months with a knee injury. Story: http://t.co/Q0wPjxjCxj

-- Arsenal FC (@Arsenal) January 6, 2014 Lukas Podolski is back to something approach full fitness now so could play on the left with Santi Cazorla switching right, while the emergence of the 18-year-old German winger Serge Gnabry offers another option. Alex Oxlade-Chamberlain, out since the opening day of the season with a knee injury, will return to training this week and, while it will take some time for him to regain full fitness, he should come back into contention in a few weeks.

The other problem with losing Walcott is that he offered cover at center forward, where Arsenal's resources are exceptionally thin. Although he missed a number of chances, Walcott was a constant threat as an unorthodox replacement for Oliver Giroud, dropping deep and linking with midfield. Losing him, surely, offers a further nudge to Arsene Wenger to invest in a new forward in January. Arsenal has made inquiries with Juventus about loaning in Mirko Vucinic and has been told Juve is prepared to sell, but only on a permanent deal that would probably cost around £8million.

The Monetenegro international has started only four Serie A matches this season as the Fernando Llorente-Carlos Tevez partnership has blossomed and is keen to find regular football. He offers the advantage that he can play either at center forward or anywhere in the line of three but Wenger's past history suggests he would baulk at paying that much for a 30-year-old. With Walcott out, though, and the squad's thinness beginning to be exposed, he may not have much option.