The Australian international went for scans following the 1-0 defeat at the Riverside and they showed what looked like a break that forced him from the field ten minutes from the end.

The extent of the injury is expected to become clearer of the next week.

It comes as a bitter blow to the 27-year-old old who has made an excellent recovery from serious Achilles problems with a handful of U21s games played in recent weeks, as he works his way back to full fitness. 

Williams, who had a loan spell at Charlton earlier this year, wasn't the only one injured during a game that saw Sunderland increase their lead at the top of the table.

Midfielder Alex Pattison, who has impressed this season, was forced off wiith hamstring problems after 24 minutes, while Joao Morelli left the ground wearing a protective boot following an injury picked up shortly before half-time.

All three are doubtful for the U21s next game, at home to Manchester City a week on Friday.

READ: Here's the match report from the game

READ: Under-21s coach Paul Jenkins gives his verdict on the game