Aiden McGeady made his first appearance since May in the first match of this weekend's four-team tournament, with the transfer speculation surrounding the Republic of Ireland winger having reached fever pitch.
In a cameo of just under an hour, the 24-year-old showed flashes of the ability which has seen Spartak Moscow bid a reported £9.5million for him and rumoured interest from Aston Villa and Tottenham.
He left the field this afternoon with his side 2-0 down to last season's Champions League semi-finalists thanks to goals from Michel Bastos and Harry Novillo.
Celtic then staged a dramatic late comeback, with Gary Hooper scoring on his debut before substitute Georgios Samaras' header made it 2-2, giving both sides three points in a tournament in which goals are also worth points.
As well as bringing in McGeady and Hooper, manager Neil Lennon handed a debut to youth player Filip Twardzik, while recalling Milan Misun, Marc-Antoine Fortune and James Forrest.
In a lively start, Fortune missed two great chances to put Celtic ahead inside four minutes, first missing a diving header after meeting Forrest's right-wing cross unmarked and then ballooning a left-foot finish over the bar upon being put clean through by Hooper.
Scott Brown had the net bulging in the 11th minute but Fortune was rightly flagged offside delivering a low left-wing cross.
A few minutes later, Misun prevented Jean Makoun giving Lyon the lead when he blocked the midfielder's finish after it beat the sprawling Lukasz Zaluska.
Midway through the half, Kim Kallstrom rasped in a volley which was blocked by Fortune after Celtic only half cleared a corner.
If that was a warning shot, Lyon landed a decisive blow in the 33rd minute.
Celtic gave away a needless free-kick near the left corner of the area, which Bastos thumped past Zaluska high into the net.
Although it was fiercely struck, the Hoops goalkeeper will have been disppointed at leaving so much space to his right after shuffling the other way.
Lyon pushed for a second goal and Novillo dragged his finish wide after a clever one-two 20 yards out.
Moments later, Celtic right-back Cha Du-Ri burst forward into an acre of space onto Forrest's ball, smashing a volley straight at Remy Vercoutre when he should have played in Fortune.
The summer signing made amends with two pieces of classic full-back play before half-time, getting in behind the Lyon defence and delivering a pair of crosses which could easily have been converted.
But Fortune nodded the first into the ground, while the second evaded the head of Hooper by inches.
Lyon, who brought off goalscorer Bastos for Yannis Tafer at the break, almost made it 2-0 when Novillo's 20-yard strike hit the crossbar.
Celtic then withdrew Brown for Efrain Juarez, with their captain having hurt himself minutes earlier challenging Kallstrom for the ball.
Brown's departure nine minutes in was almost immediately followed by Lyon's second goal, Clement Grenier sliding the ball to Alexandre Lacazette, who cut it back for Novillo to fire home via a deflection.
The goal sparked a raft of double and triple substitutions by both sides over the subsequent 20 minutes, including the withdrawal of McGeady.
One of the new arrivals, Loic Abenzoar, played in Tafer for a fine volleyed finish which was rightly ruled out for offside.
The spell also saw Juarez fire just over for Celtic from 25 yards.
With 15 minutes remaining, Lyon substitute Jeremy Pied almost embarrassed Zaluska with a volley straight into the ground which bounced up and needed fingertips to turn over the bar.
Celtic's substitutes were also making an impact, Juarez striking the post with a superb 25-yard drive across Vercoutre and Maloney cutting inside and shooting straight at the keeper.
Their persistence was finally rewarded in the 82nd minute when Forrest's cross was volleyed in by the unmarked Hooper from point-blank range.
Zaluska made a sprawling save to prevent Tafer immediately restoring Lyon's two-goal advantage.
Celtic substitute Charlie Mulgrew set up Forrest for a header which flew over before playing in a free-kick from which Samaras made no mistake.