The Gunners went top of the Premier League after they beat Fulham on Saturday and Manchester United had their match at Blackpool postponed while Chelsea dropped another two points in the 1-1 draw with Everton. After what he hopes will be negotiating safe passage out of Group H against struggling Serbians Partizan Belgrade, Wenger takes his men up to Old Trafford for next Monday night's live encounter. The festive schedule is set to throw up some fascinating encounters as United head to Stamford Bridge the week before Christmas, while Chelsea are at Arsenal on December 27. "December will be a very important month for us and for everybody," said Wenger. "When you look at the fixtures, it looks like it is a decisive time for everybody at the same moment in this league. "The fixtures of Chelsea, Tottenham, Manchester United and Arsenal are all very big in December." The Gunners should have already been in the last 16, after a 100% record from their opening three Group H games - scoring 14 goals. However, successive away defeats at Shakhtar Donetsk and Braga means they must beat Belgrade, who have lost all their five matches, to secure at worst second spot. Finishing top would require an unlikely victory for Braga in Donetsk, meaning Arsenal are therefore set for a clash with one of the seeds in the knockout rounds. Wenger, though, is not concerned. "If you want to win it, you have to play against these big teams," the Arsenal manager said. "First of all, it is not a guarantee that we play Barcelona or Bayern in the next round - there are some other teams we can play and what happens, happens. "What is important is not to focus on the teams we might play, we first have to be very pragmatic and qualify first. We will see then who we get." Arsenal will have Laurent Koscielny available after the centre-half was given the all-clear following a clash of heads with Sebastien Squillaci in the build-up to Fulham's goal on Saturday, but his replacement Johan Djourou, who is carrying a thigh problem, will not be risked. Holland forward Robin van Persie and Theo Walcott, who both came off the bench against the Cottagers, are in contention to start. Arsenal have been criticised for an apparent soft backline this season. Russian winger Andrey Arshavin, who has six goals so far, believes the Gunners need to tighten up if they are to push on and have a successful campaign. "We struggle all the time in defence. We have to score more than we concede. That's it," he said the Russian. "It is very frustrating. We are trying to improve, but we can't. "We don't just blame our defenders. Sometimes I can't run, and let defenders cross so the forwards score a goal. "It doesn't always depend on defenders. As a team we need to improve defensively."
