Chelsea will tomorrow seek to ascertain the full extent of a thigh injury sustained by Frank Lampard after the England midfielder returned prematurely from Qatar amid fears that he could be sidelined until Christmas.

Lampard suffered a tear to the outside thigh muscle of his left leg today while training for Saturday's friendly against Brazil and underwent a scan in Doha. That confirmed the damage and, after the Football Association explained the situation to Chelsea's medical department, the 31-year-old was released back into the care of the Premier League club and flew back to London.

The FA medical staff's initial assessment had suggested Lampard might be ruled out for a few weeks, though there are fears within the player's camp that the injury will prove more serious. They are concerned that he may have suffered a problem similar to the ones which ruled him out for more than a month on two occasions in the second half of 2007.

Chelsea have indicated that they would assess the extent of the problem when the midfielder reports back to Cobham. With Ashley Cole recovering from a depressed fracture of a tibia, there is anxiety at the prospect of losing another senior player.

Lampard is certainly out of Chelsea's next game at home to Wolverhampton Wanderers on 21 November. More distressing for the league leaders would be to lose the midfielder for a prolonged length of time, with awkward trips to Porto, where the Londoners will effectively contest the leadership of their Champions League qualification group, Arsenal and Manchester City to come in the next month.

The injury will focus attention further on the decision to undertake the friendly in Qatar – albeit within a Fifa-defined international window – after Premier League managers had expressed concern over the timing of the fixture. Lampard's absence would be all the more frustrating for Chelsea given that he has recently returned to his most potent form, scoring four goals in his last five games. The 31-year-old is not used to suffering lengthy injuries – he holds the record for an outfielder of 164 consecutive Premier League appearances – and would be sorely missed.

England, too, will be frustrated at his departure given that Capello has effectively been left with only three regular starters – John Terry, Wayne Rooney and Gareth Barry – to compete against the five-times World Cup winners, a reality which also casts some doubt over the relevance of the friendly. Rooney will feature and expects to begin negotiations over a new contract at Manchester United in the new year, having publicly expressed a desire to see out his career with them.

The 24-year-old placed the onus very much on the United hierarchy to resist any potential attempt by Spanish clubs, primarily Barcelona and Real Madrid, to lure the forward to La Liga. Rooney's representative, Paul Stretford, is currently banned from working as an agent having been found guilty of misconduct in his initial acquisition of Rooney's signature when he was an Everton player, but is able to operate again as of February, when Rooney anticipates talks will open with the club's chief executive, David Gill. "I've got two years left after this year so I'm sure we'll be negotiating a new deal in the next few months," he said. "It's nice to be noticed but I've said before I'm really happy at United. Unless they tell me otherwise, I can't see myself leaving. I love the place. It's 30 minutes from home and all my family and I've got a great chance of winning trophies."

Any bid for Rooney would at the very least match the £80m generated by the summer sale of Cristiano Ronaldo to Real Madrid. In that respect, United's ability to resist any interest from Spain and tie the forward down to new terms would also serve to ease any concerns over the financial viability of the heavily indebted Glazer regime.

Rooney made his initial impact with Everton, the club he had supported as a child and has continued to excel since moving to Old Trafford after Euro 2004. "It's a massive club," he said. "Although I was an Everton fan, I loved watching United play and they won a lot of trophies. I probably started from the 1994-95 season and [Eric] Cantona was brilliant.

"You looked at him and he was fearsome, and that was just on the television. Imagine playing against him."

That admiration of Cantona is surpassed by the esteem in which the forward holds Sir Alex Ferguson. "It's the trophies he's won, first of all," added Rooney. "And the type of football he wants you to play. He wants you playing attacking football all the time. Sometimes you feel you can't do it, but he keeps you going. He has that hunger. At his age, he still wants to win all the time. That's incredible to see.