Michael O’Neill wants his Northern Ireland players to go back to the future when preparing for Sunday’s Nations League game away to Bulgaria.

O’Neill called March’s friendlies away to Romania and Scotland, a 1-1 draw and a 1-0 win respectively, a “blueprint” for how he wants his young side to tackle such fixtures on the road, but other themes in recent improved performances go further back.

Northern Ireland have won four of their last six games, with clean sheets in all four victories, while set-pieces were the key to Thursday’s 2-0 win over Luxembourg as both goals were scored by defenders – Paddy McNair and Daniel Ballard.

“I think the performances in Scotland and Bucharest were almost like a blueprint for how you want your team to play away from home,” O’Neill said. “We gave away very few chances in both games, both against two teams that were preparing for Euro 2024.

“We were always a threat on the counter attack and could have won the game in Bucharest as well. It gives you a lot of belief, it gives the younger players in particular a lot of belief that they can play away from home in a difficult atmosphere and still take something from the game.

“Those games in particular were a big learning curve for the players and we refer to those two performances a lot.”

Northern Ireland have scored early goals in all of their last five games, but just as important to O’Neill has been the resilience at the back.

“Aside from the Spain game (a 5-1 defeat) we’ve only conceded one goal in six games,” he said.

“You look back to the Denmark win (last November) and we’d conceded four goals in Helsinki on a difficult night with a very, very young team and we’ve had to revert to looking at other aspects of our game to improve…

“Away from home you have to approach the game with a different mentality. It’s not that we don’t want to play on the front foot but we have to be somewhat measured in the approach.”

McNair remembers well the days when scoring from set-pieces was key to Northern Ireland’s success.

After getting the opener on Thursday following a long throw from Ciaron Brown, McNair said it was something Northern Ireland have been working on.

“Every camp we come on, we always work on attacking set plays and defensive set plays,” McNair said. “I think the defensive set-plays have been very good and the attacking set-plays the last couple of years we probably haven’t scored as many as we would like.

“I think it’s important everyone in the team chips in, so if me and Dan (Ballard) and the other defenders can chip in with the odd goal it will definitely help us going forward.”

Ballard trained alone during Saturday’s session at the Hristo Betov Stadium, but O’Neill said he had no fresh injury concerns.

McNair sat in on the pre-match press conference but O’Neill said that did not necessarily indicate the defender had been appointed captain as the manager continues to rotate the armband, declining to name a skipper before Sunday night.

Northern Ireland will be facing a Bulgaria team unbeaten in seven matches since Ilian Iliev took charge of the team, although six of those seven have finished as draws – including Thursday’s 0-0 Nations League draw with Belarus

“Obviously the manger has had a positive impact on the team and they’ve had some good results,” O’Neill said.

“The Bulgaria squad is interesting, they don’t have a huge amount of experience, only a couple of players, a bit like ourselves.

“They’re maybe a little bit in transition but the coach has brought a lot of new players into the squad and clearly it’s had a positive impact.”