Newcastle are anxiously waiting to discover whether or not Alan Shearer's playing career is over.
The 35-year-old suffered suspected knee ligament damage during his side's come-from-behind victory over derby rivals Sunderland.
Shearer fears it may end of his career, and told BBC Radio Five Live: 'It doesn't look good. They think there might be a tear in the medial ligament, and if that is the case then that will be it for me I'm afraid.
'I will have a scan on Thursday and see how bad it is.'
Shearer is desperate to be involved in Newcastle's final three league games of the season as his side push for a place in next season's UEFA Cup.
'I will be bitterly disappointed if it is (the end) because there are three huge games left for us,' said Shearer.
'I gather we are sitting in seventh now, which might get us into Europe and after what has been a tough season that would be a great achievement for everyone.
'I will just have to wait and see what the scan says. I will give it a couple of days to settle down and get one on Thursday. I'll see what it says, but it's a bit sore at the moment.'
Caretaker boss Glenn Roeder admits there are real fears over Shearer's participation again before the end of his final season.
That would rob the Magpies of their leading scorer -- he took his tally for the club to 206 and his career total to 409 with a 61st-minute penalty at the Stadium of Light - as they mount a late push for Europe following a fourth successive victory.
With three games to play, as well as Shearer's testimonial clash with Celtic on May 11 to come, that would come as a huge blow to Newcastle with Michael Owen not yet fit and Shola Ameobi having suffered a fractured jaw in Saturday's 3-1 win over Wigan.
Roeder, however, has not entirely given up hope, although he admits if the derby victory proves to be his final appearance, he will at least have gone out on a high.
'We are not at that stage yet,' he said. 'You can talk about that maybe in a week's time or four or five days' time if it turns out that is the case.
'But I will remain positive there is a chance we will still get him back on the pitch, maybe in the very last game of the season.
'If we don't, I suppose his memory of scoring then what would be his last goal would be a very, very happy one for different reasons.'