Former footballers took to Twitter to praise Celtic's win over Qarabag.
Celtic are through to the final qualifying phase of the Champions League, after beating Qarabag over two legs.
A goalless draw in Azerbaijan's capital of Baku meant their first leg 1-0 lead was enough to see them through.
In humid conditions and on a poor playing surface, Celtic weathered the home side's best efforts, with their new look defence keeping a second successive clean sheet.
Former professional footballers Trevor Sinclair, an ex-West Ham and QPR midfielder, and old Celtic favourite John Hartson both took to Twitter to praise their progression.
Celtic did not reach the group stages of the Champions League last season, and are desperate to earn themselves the chance to show what they can do.
They are a very different side 12 months on, settled under Ronny Deila after he led the team to trophy haul in his first season as manager.
Celtic find out their fate in the Champions League draw on Friday which will be held at midday in Switzerland.