Michael O'Neill has warned that Northern Ireland must have their key players available next March if they are to get past Bosnia and Herzegovina in the Euro 2020 qualifying play-offs.

An illness for Jonny Evans and injury to Jamal Lewis left Northern Ireland short-handed against Germany in Frankfurt on Tuesday and it duly turned into a punishing night as they lost their final Group C fixture 6-1, with Serge Gnabry bagging a hat-trick for the hosts.

While that was taking place, Wales' 2-0 win over Hungary confirmed Northern Ireland's remaining path to Euro 2020 will go through Bosnia.

O'Neill will be grateful that nothing as difficult as a trip to Germany lies in store, but Bosnia beat Northern Ireland home and away in the Nations League last year and cannot be taken lightly.

"If we have a full squad I believe we can beat Bosnia come March," said O'Neill, who plans to remain in charge for the fixture alongside his new duties as Stoke boss.

"If we're five or six players down it's very difficult to progress to the finals, it's as simple as that.

"We have a 25-man squad and we don't really have players outside of that.

"To get past Bosnia we will have to keep (Edin) Dzeko and (Miralem) Pjanic quiet as they are key to their performance."

Though Bosnia got the better of his side last year, O'Neill is confident a fully-fit Northern Ireland squad is much better equipped to deal with the threat this time around.

They were picked off on the counter-attack in a 2-1 defeat at Windsor Park, despite dominating possession and creating a string of chances, while Northern Ireland hit the post three times in a 2-0 defeat in Sarajevo.

Both matches came early in a process of O'Neill refreshing his squad following the 2018 World Cup qualifying campaign and a transition to a more possession-based approach going forward.

Since then the likes of Lewis and Bailey Peacock-Farrell have established themselves as key players and, after four straight losses in the Nations League, results improved considerably with four wins and a draw from their eight Euro 2020 qualifiers.

Arguably the results do not tell the full story as they led against Holland in Rotterdam until the 80th minute and only lost to two stoppage-time goals, missed a penalty as the reverse fixture finished 0-0 in Belfast, and even had a brief early lead in Frankfurt thanks to Michael Smith's strike.

"Overall this has been a good campaign for us," O'Neill said. "Thirteen points, there's no shame in that in a group with Germany and Holland. For many of our players this is their first campaign and they can only learn from nights like this.

"The players will learn both from the Nations League campaign and this campaign and the new players we have introduced have certainly been developing.

"But when you get to the play-off it's not about style of play, it's about getting through, it's as simple as that."