Massimo Donati hit an injury-time winner to reignite Celtic's Champions League hopes after an incredible 2-1 win over Shakhtar Donetsk.
Brandao handed Shakhtar a shock fourth-minute lead at Parkhead. Under little pressure, John Kennedy headed a clearance against the Brazilian, whose finish was too strong for Artur Boruc.
Jiri Jarosik levelled with a powerful left-foot volley in the 45th minute, after Srna and Dmytro Chygrynsky had collided while trying to clear Caldwell's long ball.
Donetsk came close to a late winner when Brandao blazed over from eight yards.
But Donati found the bottom corner from McGeady's ball to the edge of the box at the end of two minutes of injury time, to send the Celtic fans into raptures.
Gordon Strachan's men can guarantee qualification by drawing in Milan in their final group game in a fortnight.