Republic of Ireland striker Troy Parrott has given his support to Caoimhin Kelleher after the keeper's mistake led to Greece's second goal in their 2-0 Nations Cup win on Sunday.
Kelleher made a string of fine saves in the Athens encounter before a late blunder saw him pass straight to Petros Mantalos, who then rounded the Liverpool stopper to slot home.
"It's frustrating for all of us, there is nothing we can do. Everyone makes mistakes, Caoimh doesn’t make many," said Parrott.
"Everyone in the dressing room is behind him, but I don't think he needs it because he's strong enough mentally to deal with it.
"Obviously, it's frustrating to give a good side like this chances, especially at that time in the game when we were coming back into it and creating good chances ourselves. It's difficult, but we have to move on."
The Irish went into the game on a high after beating Finland 2-1 in Helsinki on Thursday night - their first win of the campaign and a first victory under manager Heimir Hallgrimsson.
Greece captain Tasos Bakasetas put his side in front early in the second half before Mantalos sealed the points for the Group B2 pacesetters, who shocked England with a 2-1 win at Wembley three days earlier.
"We knew it was going to be a tough game when we came. They're a good team and played well during the week [against England]," added the 22-year-old AZ Alkmaar forward Parrott.
"I think we did well, Caoimh had to make saves, of course, but that's what he's there for. I think we defended well in the first half I just think there was a little bit too much in terms of them just coming at us and us not really doing much to go back. It's about trying to create chances earlier."
Republic midfielder Josh Cullen was disappointed with the visitors' first-half display before an improvement after the interval.
"After they scored so early in the second half, I thought from then on we were the team that looked more lively. We had more control in the game," he told RTE Sport.
"I think the first half wasn't good enough from us, we tweaked a few things at the break. Just disappointed to concede so soon after half-time and I think the boys showed good courage and bravery to come back and lift the performance again."
It is three defeats from four Nations Cup games for the Republic and they face the prospect of a relegation play-off, with fixtures against Finland and England coming up next month.