BREAKING: Arsenal hit by another injury blow ahead of Manchester United clash

Arsenal have been dealt another injury blow ahead of Sunday's clash with Manchester United as Arsene Wenger confirmed Alex Oxlade-Chamberlain's knee injury is "quite serious".

The Gunners midfielder was involved in a collision with Javier Mascherano during a first-half attack in Tuesday's Champions League defeat to Barcelona, but remained on the pitch until early in the second period. Arsenal fans may question Wenger's wisdom not to replace Chamberlain immediately, given that he is now ruled out for a number of weeks and may have exacerbated the injury by trying to play through the pain. https://twitter.com/samcunningham/status/703146724353667072 https://twitter.com/JamesDallESPN/status/703146842805006337 Theo Walcott, who started Tuesday's match on the bench, is likely to replace the 22-year-old in the starting line-up for the trip to Old Trafford. United, meanwhile, have problems of their own, with Anthony Martial limping out of the warm-up ahead of Thursday's Europa League tie against FC Midtjylland complaining of a tight hamstring.