Celtic have been eliminated from the Europa Conference League after a 2-0 second-leg defeat to Bodo/Glimt on Friday morning (AEDT).
The Norwegian champions sealed a 5-1 aggregate win to send Ange Postecoglou’s side crashing out of a third European competition this season.
Celtic were also knocked out of the Champions League and the Europa League earlier in the campaign.
“It’s fair to say we weren’t at the levels we needed to be over the two games. They’re deserved winners,” Postecoglou told Celtic TV.
“It’s disappointing for us. We certainly wanted to make progress in this competition, but unfortunately our performances haven’t warranted that.
“When you look at our European campaign, ultimately, we haven’t succeeded. That’s the bottom line.
“This football club should be making an impact in Europe and it’s my job to make sure we do.”
Celtic will look to bounce back against Hibernian at Easter Round on Sunday (AEDT).
The Hoops are three points clear of bitter rivals Rangers at the top of the Scottish Premier League after 27 games.