Celtic were held to a 1-1 draw by FC Midtjylland in the first leg of their Champions League qualifier.
The Bhoys entered the competition at the second qualifying round, and were paired with the Danish side.
At stake is a meeting with either PSV Eindhoven or Galatasaray in the third qualifying round, but they are far from certain to progress after being held at home on Tuesday.
What next for Celtic? Calamitous Champions League exit leaves club floundering in Rangers’ wake
Liel Abada fired the Bhoys ahead on 39 minutes, but the complexion of the game shifted when Nir Bitton was shown a second yellow card a minute before the break.
It was 10 against 10 on 56 minutes when Anders Dreyer was dismissed, but it did not impact on Midtjylland who secured a draw heading into the second leg when Evander Ferreira scored on 66 minutes.
The second leg takes place in Herning on July 28.
Little hoping to draw inspiration from other Scottish Olympic legends
Brentford confirm signing of £13.5m Ajer from Celtic
Ajer completes Brentford medical ahead of £13.5m move from Celtic - reports