The midfielder, who played in every game of Saints’ Championship promotion winning campaign, did the damage not long after coming on for his first preseason match.
Cork has been away with Team GB at the Olympics and was supposed to get 45 minutes of action for Saints to bed back in ready for the big kick-off at Manchester City a week on Sunday.
However, after going over on his ankle he is now very much touch and go to be ready that quickly.
Saints boss Nigel Adkins said: “Unfortunately we’ve lost Jack Cork by the look of it.
“He’s got his ankle all strapped up now.
“We will have to wait and assess but it looks as though he’s gone over on his ankle.
“That’s not ideal because it’s his first period of time in pre-season and we wanted to get more from him but it looks like he’s going to have a spell on the sidelines now.” The game itself was a generally quiet affair in terms of chances.
Jon Stead gave City the lead just before half-time but Billy Sharp levelled things up in injury time at the end of the game.
Adkins was pleased with the progression he saw from his team.
“The KPI (key performance indicator) before the game was how we press the ball and we’ve been working on that so we’ve got an assertive press in the attacking third of the pitch to win the ball high up,” he said.
“We played a 4-4-3 system all preseason.
It’s new to the group of players that we’ve got an I think we’ve progressed very well through the pre-season.
“The way we pressed the ball, especially in the first half, we were very assertive with it, won the ball high up the pitch and on the odd occasion that we lost the ball we won it back very quickly.
That was the main KPI that I wanted out of them and I was very pleased.
“Second half we changed it round a bit to introduce Jack Cork whose been with the GB squad and Steven Davis who needed game time so maybe the tempo wasn’t as aggressive as the first half.
“First half we had some good opportunities to score and second half as well.
“Billy came on there and the one occasion we did put the ball in the aerial position for Rickie to knock down Billy has gone and scored.
“It’s different ways to win football but the ethos is still to pass it and pass it quickly and it was very pleasing when you look at it.”