Partick Thistle are looking to sign a defender before the transfer deadline after Callum Booth was ruled out for three months.

The left back was injured in a clash with St Johnstone's Alan Mannus in last weekend's 1-0 defeat at McDiarmid Park and was substituted immediately.

Thistle manager Alan Archibald revealed Booth has torn his posterior knee ligament and has been told he will be sidelined for around 12 weeks.

The 26-year-old has played in all but one of Thistle's games this season as they progressed to the quarter finals of the League Cup and suffered a difficult start in the Premiership.

Archibald will now enter the market ahead of next Thursday's summer transfer Deadline Day, to replace Booth.

"There wasn't going to be [any more players coming in]," he said, "We were done, but unfortunately for us Callum Booth picked up a bad injury last week.

"He'll be out for up to 12 weeks now so we'll probably have to go back in and get a bit of cover for the full back area."