It is a difficult start for Northern Ireland in World Cup qualifying, where they will be expected to beat Luxembourg but be huge underdogs away to Germany in their second fixture.

Northern Ireland last faced Luxembourg in November, when they threw away a two-goal lead in a dramatic draw, which was still enough to finish top of their Nations League group.

Southampton midfielder Charles says it will be a “tough game” in Luxembourg but O’Neill’s youthful side have learnt their lessons from November.

“The main thing we can learn is we had chances to kind of kill the game off, obviously we didn’t do that.

“And, also on the flip side, just to be able to stay solid at the back, which normally we are, apart from the odd occasion.

“It was a bit disappointing to not win that game, so that’s something we learned that day, to see our games.

“I know it’s going to be a tough game, so we will just go there and try and win the game and that can give us the confidence to go into the next game.”

Northern Ireland have a number of injury concerns heading into the World Cup double header, including goalkeeper Pierce Charles and the defensive trio of Daniel Ballard, Brodie Spencer and Ciaron Brown.

Charles said he has “not got any worries” about players who will come in for those sidelined, but admitted he was “gutted” for his younger brother, who had established himself as O’Neill’s number one.

Bailey Peacock-Farrell, who Charles displaced, is an experienced option and could get the nod to start in Luxembourg and Germany, while O’Neill also has Luke Southwood and Stephen McMullan at his disposal.

“He was doing so well at Sheffield Wednesday and he was playing well for us, so it’s a bit of a blow for him, and for us really.

“But we’ve got the players to come in and do a good job in that position.”