Three late goals gave Germany victory in Friday night's European Championship U21 qualifier at Mourneview Park.
Roy Millar's side defeated Finland U21s last week
Rouwen Hennings' double strike and a cracking 25-yard effort from Mesut Ozil gave Germany the points.
"I think 3-0 flatters the Germans. We had chances to open the scoring and they only took the lead late on," said N Ireland manager Roy Millar.
Thomas Stewart was dangerous in attack but the N Ireland striker wasted a good chance to score in the first half.
"I am very disappointed, mainly for the players, after the performance they put in," added Millar.
"The display from my team pleased me. The two midfield players, Kieran McKenna and Robert Garrett played very well and up front Thomas Stewart and Daryl Fordyce never stopped working.
"We were strong at the back for most of the game and everyone deserves credit for their performance.
"They were there for the taking before the goal arrived. We had to push for a
goal and that left us a little bit more open at the back than we had been
earlier and they scored again with two late goals.
"After that performance we deserved something from the game, but sometimes you
don't get what you deserve in football."
When Hennings struck 20 minutes from time Northern Ireland hearts sank and
Ozil's sweet finish secured an opening game win for the Germans.
Hennings' second of the game as injury-time loomed sent a large German support
away happy with the effort of their team.
Northern Ireland, who beat Moldova 1-0 in their opening qualifier, travel to play Luxembourg on Wednesday.
N Ireland U21: Tuffey, Callaghan, Taylor, McArdle, Casement, Garrett, Turner, McKenna, Stewart, Fordyce, Buchanan.
Germany U21: Fromlowitz, Boenisch, Castro, Schonheim, Schwaab, Aogo, Ebert, Kruska, Polanski, Rosenthal, Dejagah.
Referee: Paolo Tagliavento (Italy)