Scott Brown and Moussa Dembele both took heart from Celtic's 2-0 home defeat to Barcelona, despite the fact the result dumped the Hoops out of European competition.
Lionel Messi's first-half goal and his penalty shortly after half-time at Parkhead confirmed Celtic will finish bottom of Champions League Group C.
And due to their head-to-head record against Borussia Monchengladbach, they will miss out on Europa League football whatever happens against Manchester City at the Etihad in two weeks' time.
Brendan Rodgers' men had their chances against the reigning Spanish champions but could not spoil their clean sheet, with Dembele seeing his dipping drive saved in the 36th minute.
Celtic captain Brown told BT Sport: "I think we did really well in the first half. We had a clear chance and Craig [Gordon] made a great save on that [Luis] Suarez header.
"It's not been our day but we've played really well and dug deep to show that we can compete in the Champions League.
"It's a learning curve but we've showed quality against a top quality team.
"Hopefully we'll be back next year.''
Former Fulham striker Dembele was similarly optimistic.
"When you play against Barcelona you don't get a lot of chances and you have to make sure you put them in the back of the net,'' he said.
"We didn't manage to do that today but we showed that we are strong together and that's a positive.''