Manu Tuilagi is a serious doubt for England's autumn international fixtures after Leicester boss Richard Cockerill revealed the powerful centre has suffered a suspected torn pectoral muscle.
Tuilagi sustained the injury in the Tigers' 31-6 victory over Newcastle in the Aviva Premiership, his first outing since starring for the British and Irish Lions in their successful tour of Australia over the summer.
"Manu Tuilagi has a suspected torn pec muscle in his chest," said Cockerill.
"He's having further investigation into that. Until we know exactly what the damage is it is hard to tell how long he will be out, but you'd think it is certainly weeks, leading to months potentially, rather than days.
"He did it in a tackle in the final minutes of the game on Saturday. Hopefully, he has just partially torn a pec muscle - we're having it assessed. But it could mean surgery, depending on how severe it is."
His injury is another blow for national team boss Stuart Lancaster, who is already without Tuilagi's Leicester team-mate Tom Croft and Saracens centre Brad Barritt for November's internationals due to knee and foot injuries respectively.
If Tuilagi's injury is severe, he too would likely miss the entire autumn campaign, which begins against Australia at Twickenham on November 2 and is followed by matches against Argentina and New Zealand on November 9 and 16 respectively.
Billy Twelvetrees and Kyle Eastmond are now the remaining fit centres in Lancaster's elite player squad.
Samoa-born Tuilagi underlined his importance to both club and country with a strong showing against the Falcons, playing a heavy role in two of Leicester's five tries, before being withdrawn with five minutes to go.
Leicester backs coach Paul Burke said afterwards the 22-year-old was taken off as a precaution after suffering cramp.
Last week, Tuilagi, who signed a new long-term contract with Leicester in May, apologised for playing a prank on Prime Minister David Cameron during the Lions' visit to Downing Street.
Tuilagi gave Cameron 'bunny ears' while stood behind and to the left of the Conservative Party leader as a group of players and management posed for a photo at the function to honour the Lions' 2-1 series victory over Australia.
Former England hooker Brian Moore branded Tuilagi a "complete and utter prat", while his Tigers coach Cockerill described the actions as "daft".