Ange Postecoglou hopes his first Celtic win will give his players belief but he was underwhelmed by the majority of their performance in the Czech Republic.
Celtic won 4-2 against Jablonec in the first leg of the Europa League third qualifying round to make it victory at the fourth attempt for the Australian manager.
Goals from summer signings Liel Abada and Kyogo Furuhashi had Celtic two up inside 16 minutes.
But they needed a last-minute diving header from Ryan Christie to restore their two-goal cushion for a second time after conceding sloppy goals either side of a James Forrest strike.
Postecoglou said: "The result is obviously a positive one. I think it's important, particularly for the players, who have been working hard. Every competitive game we have had an opportunity to win, which we haven't done.
"It's a reward for the players and hopefully gives them confidence and belief moving forward.
"The performance was OK. We started really well, the first half hour was excellent, and controlled the game. I felt we lost our way a little bit after that especially second half, and lost control of the game.
"Second half we were doing OK but didn't really control the game the way we should have to make sure we won the game more comfortably."
A simple ball over the top allowed Vaclav Pilar to run in between Nir Bitton and Carl Starfelt to net the home side's first goal past a static Joe Hart.
And Celtic were caught out late on, with Hart chipped before the ball went in off the post and Bitton.
When asked about Celtic's defensive frailties, Postecoglou said: "It's not so much one aspect. Yeah, we scored four goals but had unbelievable opportunities to score more.
"I just felt we didn't control the game as well as we could have done after 35 minutes of the game.
"Yeah, defensively we were really open but part of the reason for that was us giving the ball away unnecessarily. We were just making poor choices. We weren't really compact when we did want to press.
"A whole range of aspects left the game really open. We still had chances at the same time but it's not the way I want us to play."
Playing 24 hours after joining from Tottenham, Hart looked slightly hesitant at the first goal but was left stranded for the second goal after Tom Rogic lost the ball with both Bitton and Anthony Ralston out of position on the right side of Celtic's defence.
On his decision to put the England international in for his debut so soon after signing, Postecoglou said: "It's not ideal but we have had to to this the last few games. We did it with Carl and Kyogo at the weekend and when Liel came in. I just don't think we have time to waste. We brought these guys in for a reason.
"Joe felt good about starting. He's had a pre-season so there's nothing fitness-wise to worry about.
"He didn't have a lot to do. He pulled off an important save right at the end but he'll get a better understanding of how we want to defend. I'm sure that experience will help him."
