The Rovers midfielder limped out of the game at the Amex Stadium after thirty minutes of the first half with a hamstring strain.
Williamson will have a scan to discover the extent of the injury, but it is hoped that he'll be available after the international break.
"Unfortunately we lost Lee Williamson," said the Rovers manager.
"It is his hamstring, it is disappointing that he's had to come off, so we'll see how it goes over the break and hopefully he'll have time to recover.
"But we're fortunate that we've got players coming back that will add something to the squad."