THOMAS BUTLER is out until Christmas after having an operation on his injured ankle.
The winger had surgery to remove a bone spur from the joint and will be sidelined for six weeks.
His continued absence means Mick McCarthy may be more eager to try to extend the loan of Middlesbrough teenager Stewart Downing, who has been excellent in his two games since arriving from the Riverside.
Butler hasn't played since Sunderland's goalless draw at home to Cardiff on October 14, when he went off at half time with a sore ankle.
An attempted comeback to training saw him break down again and it was decided surgery was necessary to solve the problem.
Boss Mick McCarthy said: "It's disappointing for Thomas and us and we just have to hope he comes back strong when he recovers.
"He was doing well for us and he's gutted to be missing out for a few more weeks, but he'll get over this and be fine."
Although naturally right-footed, Butler was McCarthy's first choice on the left wing before bowing out through injury.
After trying Tommy Smith and Alan Quinn on that flank, McCarthy decided to move a week ago to recruit Downing on a one-month loan.
The 19-year-old has been impressive since arriving, scoring one goal and making another in Tuesday's 3-1 win at Gillingham and delivering a string of dangerous crosses in Saturday's 0-0 draw at promotion rivals West Bromwich Albion.
It would be a surprise if McCarthy has not already asked about the possibility of keeping Downing for longer.
A permanent move for the England Under-19 international would be the fans' preference, but Boro are unlikely to allow that to happen – certainly not immediately – and a loan extension is possibly Sunderland's best bet.
Downing is already being tipped for big things, despite starting as many league games in a week for Sunderland – two – as he did in three seasons for Middlesbrough.
Sunderland striker Marcus Stewart says the Teessider has the potential to go all the way. He said: "He's a fantastic prospect, for English football, not just for us.
"There aren't that many natural left-sided players around at the moment and when someone with his pace and ability comes along it is rare. He is good with both feet and that could be good news for England.
"He has represented his country at Under-19 level and every level before that. He will be hoping to progress into the Under-21 set-up and beyond.
"There is no reason why he cannot go on to play at senior level for England because we don't have many natural left sided players.
"I'd love him to stay at Sunderland for more than a month. As a striker you want to feed off crosses into the box and Stewart provides that.
"At Gillingham, he created one for me in the first half which I should have scored and he created our second goal for John Oster and scored the first himself."