Club Atlético de Madrid secured their place in the UEFA Europa League round of 32 courtesy of a slender victory against Celtic FC, who can still qualify from Group I nonetheless.
A powerful drive from Arda Turan on the half-hour mark ended the hosts' ten-game unbeaten run and cemented the 2010 winners' position at the top of the section. Celtic, three points behind second-placed Udinese Calcio, will progress alongside Atlético if they defeat the Serie A side in Italy on 15 December.
Arda was also involved in a move from which Atlético should have taken the lead inside a minute, delivering a ball into the box which Diego Godín directed across the penalty area. The unmarked Eduardo Salvio, with the whole goal to aim at, somehow placed his header wide.
Reprieved, Celtic responded with Giorgos Samaras bringing a reaction save out of Thibaut Courtois after Daniel Majstorovic had glanced on a Ki Sung-Yong corner. Samaras then got around the back of the visitors' defence, only for none of his team-mates to be on the end of his inviting cut-back.
The goal which both teams had been threatening soon arrived, though. Diego's corner from the right was cleared by Majstorovic as far as Arda, who, after taking one touch to control, unleashed a shot which the unsighted Fraser Forster could only help into the net.
Celtic, who had Joe Ledley carried off in the first half, introduced Gary Hooper at the break. However, even with their top scorer on the field alongside Samaras, Anthony Stokes and James Forrest, the Hoops failed to extend Courtois until the midway point of the second period, when the on-loan Chelsea FC goalkeeper tipped over Ki's curling free-kick.
Always a threat, Atlético were denied a second late on by Forster, the keeper quick off his goal line to save from Juanfran. The only negative for Gregorio Manzano's men was a booking for Gabi, who will miss the matchday six date with Stade Rennais FC as a result.