Collins expressed his disappointment at the manner of the goals the Republic conceded, particularly the first goal.
Ioannidis’ opener came five minutes after the restart as he curled home from outside the area after being afforded too much time and space.
The second from Tzolis with five minutes remaining came from a swift counter-attack and a confident finish.
“I think [for the first goal] we lost our shape a little bit, it was a good finish, but I think there were things we could have changed,” Collins explained.
“I thought we came out sharp in the second half and were on top, but I think that goal took a lot out of us unfortunately.
“When we’re on top and at home we need to find an equaliser and we need to chase it, counter-attacks happen but the first goal was really frustrating.”
Brentford centre-half Collins acknowledged that the Republic played much better than they did in their opening group game against England where they lost 2-0, particuarly in the first half.
He did concede, however, that they need to develop a clinical edge to get anything out of their next two games, an away double-header against Finland and Greece in October.
“I think first half we were very dominant, and they couldn’t get through us,” he continued.
“We were good on the ball and we created loads of chances, but we need to score.
“We need to put ourselves ahead and give ourselves something to fight for in the game.”