Hearts manager Paulo Sergio has attributed Celtic's unbeaten run to growing confidence after exiting Europe.

Leaders Celtic face Hearts on Wednesday at Tynecastle, the scene of their last Scottish Premier League defeat on October 2 last year, looking to move four points clear of second-placed Rangers.

Neil Lennon's side last dropped points on October 29 and have since embarked on a 12-match winning run in the SPL.

And Sergio, who first met Lennon in the United States while manager of Sporting Lisbon, believes the Bhoys have benefited from no longer being in the Europa League.

"What they did in the European competitions gave them a lack of confidence," Sergio said. "After they came out of European competition they started to win games in our league and victories bring confidence.

"They are so strong now, better than at that time (October 2). At this moment they are the team in the best position, that's clear.

"Celtic have lots of good things. They are a strong team with very good technical ability, fast players. They have all they need to fight for their goals.

"They don't need to hear me speaking well about them. They know they are good enough."

However, Sergio is confident that, despite his side's financial problems and the unavailability of first-choice goalkeeper Marian Kello, victory is possible on Wednesday.

"We should know and recognise their capacity and our capacity too," he said. "In 10 games we have the chance to beat Celtic two or three times. I hope tomorrow is going to be one of those times."

Sergio recognises his side must improve on their performance on Sunday, when St Johnstone earned a fifth-round replay in the William Hill Scottish Cup despite being reduced to 10-men while Hearts were leading.

Sergio said: "We are playing against a strong team. They are improving all season and we have to be at our best level to have a good result.

"We have to be much better than we were in the last game at home. Small things make all the difference in the end."