Davies, who has just completed his move from West Bromwich Albion after a season-long loan at Villa Park, suffered the injury in the match at Arsenal last March.
It looked as though Davies, who was called up for Fabio Capello’s first ever England squad, would be out until October.
Davies: Will return to the heart of Villa's defence sooner than expected
But the player was targeting a mid-September return and now O’Neill is hoping for an even earlier date.
'He’s doing remarkably well and has actually been training with us,' said O’ Neill.
'We thought it would take a bit of time so it’s a surprise for us and a credit to him and the medical staff who have looked after him brilliantly.'
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