Harry Arter believes Ireland did not deserve to lose to Finland at the Aviva Stadium on Sunday in the Nations League.
The game, a 1-0 defeat, was Stephen Kenny's first home match in charge of the Ireland senior team. His first game, away to Bulgaria, finished 1-1 on Thursday.
"It's hugely disappointing," Arter told Sky Sports.
"I felt we didn't deserve to lose the game. We probably didn't do enough to get a goal but I felt like we defended well.
"We've got to make sure that we see games out that are 0-0. If we don't create an awful lot, we've got to make sure that we don't concede.
"I felt in the attacking areas that we could have been better. I don't think we had enough conviction up top. That's not criticism of the lads that were playing there; as a team, whether the build-up was too slow or that final pass let us down... I felt we built up from the back very well but we lacked that killer instinct which at international level [you need to have].
"It's tough for the manager. He's been with the lads for the best part of four days, two days before our first game. You can see we're trying to change the style and, for me, I feel long-term that it's the way forward.
"We'll be stronger for this, for these last two games.
"We've got a lot of new faces in the squad. The front three, obviously Callum [O'Dowda's] been with us a few times but the two lads up top (Adam Idah and Aaron Connolly), they're fantastic prospects and someone the manager has worked well with at U21 level.
"Their qualities are what we lacked in the past: That directness and pace. We just have to bed them in. It's a tough ask for this group of players, a new manager, hardly no pre-season games behind us as a group and as individuals."
Ireland's next game is on the Euro 2020 playoff against Slovakia on October 8th. Robbie Brady, who started Sunday's game in midfield with Arter, feels the more time this group spends working with Stephen Kenny, the better they will become.
"It's going to be a quick turnaround," said Brady.
"There's a very important game to come next. We'll be looking to make things right and show the best of us.
"The more we work with this coaching staff and this manager, the best will come out of us.
"It's not an excuse. It is difficult when someone puts a new stamp on it and changes things up. It's not only that. It's still pre-season and the lads are only back a couple of weeks; some of us are only playing together for the first time."