Celtic keeper Craig Gordon refused to be downbeat after missing the chance to reach the Europa League knockout phase with two games to spare.
Ronny Deila's side were held to a 1-1 draw by Astra Giurgiu in Romania.
A win would have secured qualification from Group D, but Celtic know a home victory against Salzburg next time out will see them through.
"We still got a point and we have to remain positive and try to win the next one to get through," said Gordon.
The Scottish champions had the best of the first-half, although goalkeeper Gordon, who has been outstanding in Europe this term, had to pull off a brilliant stop to deny Seidu Yahaya.
Ronny Deila's outfit notched the goal their play merited through Stefan Johansen, and could have added to their lead after the break.
But they were hit with a sucker-punch 10 minutes from time when William de Amorim curled a cracking effort into the top corner, leaving Gordon with no chance.
"We're unfortunate not to take the three points," Gordon told BBC Scotland. "We felt fairly in control of the game, but it was a great strike - he won't hit many better than that.
"They had a few chances but not many and I thought we dealt with it fairly well, but we didn't manage to keep the clean sheet that would have got the three points."
Celtic substitute Leigh Griffiths had a late goal ruled out when he was judged to have fouled Astra defender Cristian Oros, and Gordon reckoned it was a close call.
"There wasn't a great deal of contact," he added. "It was very slight, you can see why the referee's given it.
"There was very little contact if any but in these pressure situations, at that time of the game, it's understandable why the referee came to that decision."
The match in Romania, which saw Astra's Vincent Laban sent off late on for a lunge on Charlie Mulgrew, was almost postponed due to heavy fog. But the conditions were not a problem for Gordon.
"I'm used to the haar in Edinburgh," he said. "We prepared as normal and when I went out I could see the other goal so it was fine to play."