O’Neill was without central defender Bobo Balde and striker Chris Sutton – who can also slot into defence – after they suffered hamstring strains following their UEFA Cup triumph against Stuttgart on Thursday night.

Despite grabbing the winning goal, O’Neill admits Mjallby is nowhere near full fitness after spending much of the season on the sidelines with an ankle injury, but the Hoops boss reckons the rest of the side’s performances in the 3-2 win can be put down to tiredness following their exertions in Germany.

He said: “I absolutely put it down to Thursday night. Johan Mjallby came in today and he was very tired by the end of the game but he still managed to get up and head the winning goal.

“He isn’t remotely near being fit and has had an injury-stricken season but he has great heart and he showed some heart to keep going right to the end.”

Celtic got off to a dream start when John Hartson opened the scoring after just 60 seconds before clinching a second goal midway through the opening 45 minutes, but that was cancelled out by a double from Tom McManus.

Just when the Edinburgh side thought they had held on for a valuable point at Parkhead, Mjallby snatched the win for Celtic after 91 minutes and O’Neill insists Hibs squandered one of the best opportunities they will get to take points from his side.

He said: “If I were Bobby Williamson before this game, I would have sensed that this was the day that something could happen.

“We would have been vulnerable after Thursday night and, when he looked at the team-sheet, he would have seen that we had some of our big players out.

“That’s why it was so pleasing that we managed to win the game. Whether we would conjure up the winner or not is in the hands of the Gods and we were so determined to win the game that it was left wide open to Hibs and they could have won it instead.

“But it was important that we got the three points because that has kept the championship alive and we won’t be relinquishing it so easily.”

But Williamson reckons his side were unlucky not to take all three points when McManus was denied the chance of a hat-trick by a lineman’s offside flag.

The youngster thought he had netted early in the game to cancel out Hartson’s opener and the Hibs boss claims his side were unfortunate not to be handed the goal.

He said: “I’m shouting for a goal because he was challenging for the ball at the time and I don’t see how he could have been offside.

“The ball was in the air for a long time, and I would have to see it again, and if the lineman has got it right then so be it but I don’t see how that can be.”

McManus was denied the opportunity to grab his hat-trick later in the game when a clash with Celtic goalkeeper Javier Sanchez Broto left him with an injured arm and he was forced to make way for John O’Neill.

Williamson added: “Tam went in for the challenge and, fair enough, he was offside but I still felt the goalkeeper was a bit reckless with his challenge.”