Lawrence Shankland’s early penalty gave the Jambos a lead but it was swiftly cancelled out by a spot-kick from Stefan Schwab.

Shankland then had a goal ruled out for offside following a VAR check before a 75th-minute strike against the run of the play from Andrija Zivkovic gave the Greeks a crucial advantage.

Hearts must now pull off a victory in the intimidating Toumba Stadium in Thessaloniki next Thursday if they are to qualify for the group stage, but McAvoy remains optimistic.

“We knew it was going to be a tough game and a tight affair,” said the head coach. “It was disappointing that we scored then they got a penalty so early after it.

“Then we score with Shanks and the elation then turned to a sour note when it got chopped off. Then they score from a corner.

“As for emotions, I’m disappointed with the result but in spells I felt our shape without the ball was really good. They’re a good team and they try to hit on the counter and there were some pleasing moments.

“We know what we’ve got to do now – we’ve got to win the game and I believe it’s possible for us to do that. That’s what we’ve got to look forward to in the next leg.

“We just need to make sure we’re prepared as best we can for going to Greece next week knowing that we’ve got to go and win the game.”

McAvoy believes Hearts showed in Thursday’s first leg that they have enough attacking threats to score in Greece next week.

“I thought when we got into good areas we caused them problems,” he said. “First half their keeper made a fantastic save from Shanks, so we know we’ll create chances.

“I think our wide players could cause them issues. We’ve got a good squad. We’ll deal with Dundee as best we can (in the cinch Premiership on Sunday) then really focus on what we’ve got to do in Greece.

“We’ve come a long way since myself, Steven Naismith and Gordon Forrest came in (as a management team at the end of last season) and the players have great belief in themselves.

“That’s important going forward and we’ll have that at the forefront of our minds when we go to Greece next week.”

Hearts suffered a further setback as they lost Barrie McKay to injury midway through the setback.

“It’s too early to say, he felt something in his knee,” said McAvoy, when asked about the extent of the problem. “The guys have to assess it to find how bad it is but it’s too early at the moment.”