To make things worse, his defensive midfield partner James McCarthy is also to be assessed after suffering a hamstring injury late on.
Barry - who had passed a late fitness test on an ankle injury to start at the Stadium of Light - went down in pain after a late challenge by Jordi Gomez and was replaced by Darron Gibson on 11 minutes.
It initially looked like it was the same ankle he had bruised against Lille on Thursday but there were fears Barry might have broken his leg, with some alarmists (and apparent medical experts) on Twitter fearing for his season or even career.
Barry went to hospital for x-rays during the game and returned wearing a plastic protective boot to travel back with the team.
Liverpool Echo reporter Greg O'Keefe later revealed that Barry has spoken to his teammates and was confident it wasn't broken, though he needs to wait for confirmation from the medical team.
Martinez then confirmed in his post-match briefing that he was waiting on news of possible damage to Barry's ankle rather than any broken bones.
Meanwhile McCarthy suffered a hamstring strain in the closing stages of the game but managed to play on, clearing Wes Brown's header off the line in injury time.
Martinez confirmed the midfielder will be assessed, with the only positive being the looming international break and the chance to recuperate before the West Ham game on November 22.
After Martinez spoke of their importance to the team in Friday's press conference it is typical Everton that both Barry and McCarthy would go on and get injuries.
At this stage it is too early to speculate, even if many are fearing the worst. We can only hope their injuries aren't serious, meaning they may be able to play when the Premier League returns in a fortnight's time.