Manchester United defender Rio Ferdinand has lost his battle with a back problem and will be sidelined for up to six weeks.

Ferdinand will sit out Sunday's Premier League showdown at Stamford Bridge and Red Devils team-mate Wes Brown admitted that the 30-year-old has tried to play through the pain for months.

Brown said: "He's been getting a lot of pain for a long time so he's sorting it out now."

The England international has come under fire recently for numerous poor performances.

Brown added: "When he comes back he'll be a lot stronger.

"If you're not fit and want to play it's very hard. Believe me."