Barry started the match despite an existing complaint with his right ankle and his afternoon ended early after he was caught by a late challenge from Jordi Gomez.
After the former England international left the field on a stretcher there were initial concerns Barry had suffered a broken leg.
X-rays allayed those fears but Roberto Martinez remained cautious over when the holding player might return.
"I am happy to confirm that it's not the broken leg we were worried about," he told reporters. "There is damage to the ankle we must assess.
"The tackle is an early one in the game, there is a lot of energy and it is unfortunate. As he is falling, he stretches his leg. There is no intention whatsoever – it is just unfortunate.
"Gareth Barry is not the sort of player to simulate. We knew he was in trouble the minute he went down."
McCarthy completed the 90 minutes - making a vital goal-line clearance to deny Wes Brown in stoppage time despite soreness in his hamstring.
"We are going to assess James," Martinez added. "He was feeling his hamstring towards the end of the game but he wanted to stay on the pitch because we had used all three subs.
"It is a bit of a concern because he had the same injury a few weeks back when he missed the game against Manchester United and it is in that area.
"We are hoping that it is more fatigue than a soft tissue problem. We will assess him in the morning."
