The third match of their pre-season tour brought their first win, their goals coming from Gary Hooper and Anthony Stokes.
That it came against inauspicious opposition, Bundesliga Two club Vfr Aalen, will matter little. The match with Ajax will provide Celtic with a stern test, but they showed enough fight to recover from their hosts' fourth-minute opener yesterday.
Hooper, Celtic's top scorer for the past two seasons, got them off the mark in the 63rd minute after he converted a cross from Dylan McGeouch. Not to be outshone, Stokes contributed what proved to be the winner 14 minutes from time after a rare piece of creative play, which involved Scott Brown and James Forrest.
With only two weeks until they compete in their opening Champions League qualifier – the draw for which will me made on Friday – the examination of Celtic's readiness is being stepped up significantly, the Ajax match quickly followed by meetings with Norwich City and Internazionale at Celtic Park.
There remains clear evidence that some rustiness remains as the Clydesdale Bank Premier League champions continue to integrate all of their first-choice players back into the side. Nevertheless, Neil Lennon is content that progress is being made.
The manager showed his frustration at how hard his side made it to overcome Aalen, though. Sponsored by an energy technology company, and housing rows of solar panels along the roof of the two stands at their Scholz-Arena, they proved too bright for a Celtic side that were not at full power in the first half.
Of the three teams the Celtic manager has selected to start in this tour, the one captained by Kris Commons last night was by far the most recognisable. The players who have given dispensation to return late from international duty are only now getting up to speed, and Victor Wanyama and Mikael Lustig had progressed sufficiently to feature from the start.
They linked up with Kelvin Wilson and Charlie Mulgrew in a conventional back four, but despite their physical presence and extensive experience they got off to the worst possible start.
By the time Benjamin Hubner had opened the scoring, Fraser Forster had already made an important save from Marcel Reichwein. The Celtic goalkeeper appeared to have thwarted Aalen once more when he blocked Hubner's initial close-range shot, the opportunity arriving for the defender following a head flick from Robert Lechleiter, who had stolen in front of his marker at a free-kick. However, the ball dropped back to Hubner and he converted dutifully from just five yards.
Celtic showed no real urgency to regain parity prior to the interval. Indeed, Forster was still much the busier of the two goalkeepers, his best save coming on 31 minutes when he touched another well-struck shot by the elusive Reichwein on to his crossbar.
The paucity of Celtic's attacking threat in the opening half could be measured by the fact that their best chance – which fell to Stokes – amounted to little more than a blocked shot, with Daniel Bernhardt, the Aalen goalkeeper, content to watch the danger averted by his defenders.
Recognising the need to inject some urgency into his side's play, Lennon replaced Biram Kayal with Scott Brown for the second half, and soon added McGeouch, Paddy McCourt and Mo Bangura to the action.
The response was almost immediate. McGeouch's cross set up Hooper for his goal, then Brown played his part in Stokes' winner before the captain found time to pick up his second booking of this tour.
More importantly, Celtic got their first win and now travel to the Netherlands in both better condition and in a better mood.