Tomas Czevankara: New signing ‘ready to go’ for Celtic vs Hearts with Jonny Kenny a doubt

Kenny injured his calf during Thursday’s 2-2 Europa League draw with Bologna, but Celtic’s attacking options have been bolstered by the return to training of Kelechi Iheanacho, who has not featured since limping off in the Premier League Cup final against St Mirren last month.

“It might be a bit difficult to start him in a game at the moment, but at least he will be available,” O’Neill added of the Nigeria international.

Hearts beat Celtic 3-1 at Tynecastle in October – Brendan Rodgers’ final game – and triumphed 2-1 at Parkhead in December when Wilfried Nancy began his ill-fated spell.

O’Neill handed the reins to Nancy after winning all six of his home matches in a spell in charge following Rodgers’ resignation, and he has maintained that perfect record since returning to the club.

However, Hearts have been the outstanding Scottish team this season, and O’Neill knows how important the game is in the title race.

“It’s going to be very big, there’s no doubt about that,” he said. “If we get beaten, it will be a long way back for us.

“I think it’s not the end of the road, but nine points will be enough to get it back in the remaining 15 games.”

O’Neill praised the work done by Hearts coach Derek McInnes and expects a “fiery” reception on Sunday.

“Wow, it’s been really great,” he added when asked about Hearts’ season so far.

“I was about to say they benefited from Celtic and Rangers stumbling, but that’s not the case. They relied on themselves and that’s a huge credit to them really.”