New Fenerbahce coach Jose Mourinho will have to mastermind a second-leg comeback by his side to keep their Champions League qualification hopes alive after they lost their away tie 2-1 at Lille in third round qualifying on Tuesday.
An Edon Zhegrova winner in injury time gave the hosts the advantage after Irfan Kahveci's fine second-half free-kick had wiped out an early opener by Tiago Santos.
The fourth-placed side in France's Ligue 1 last season inflicted the first defeat of Mourinho's reign after the 61-year-old took charge in June and guided Fenerbahce through second-round qualifying with two wins against Swiss side Lugano.
"(It's) 2-1 at half-time (after first leg) so let's go, let's go to Kadikoy (Fenerbahce's stadium), let's go with a yellow wave and we are waiting for them," Mourinho said at his post-match press conference.
With 12 minutes gone, Portuguese right-back Santos beat two opponents down the flank and fired across goal from a tight angle, with the ball squeezing across the line via goalkeeper Dominik Livakovic.
Just after the break, Allan Saint-Maximin had two good chances to level for Fenerbahce inside the space of three minutes but was denied on both occasions by Lille stopper Lucas Chevalier.
With 13 minutes remaining, Kahveci won and then superbly converted a free kick from just outside the Lille box to level the match.
The Turkish attacker's whipped left-footed strike left Chevalier rooted to the spot as it flashed over the wall and into the top corner.
But as the clock ticked past 90 minutes, substitute Zhegrova drove in from the right and his deflected strike looped past the stranded 'keeper to give Lille victory.
The winner of the two-legged tie will progress to the play-offs for the Champions' League group stage, where they will face either Slavia Prague or Union Saint-Gilloise.
- DRESSERS TO THE RESCUE -
Elsewhere, Scottish Premiership runners-up Rangers grabbed a 1-1 draw away to Dynamo Kyiv thanks to Cyriel Dessers' equaliser four minutes into added time in Lublin, Poland.
Andriy Yarmolenko had opened the scoring in the 38th minute following a defensive mistake.
The pre-match build-up in Poland was dominated by news that two of the VAR officials scheduled to be in place for the tie were arrested for a drunken escapade.
Reports said three intoxicated men were detained by police in the early hours of Tuesday after removing a road sign.
Swedish club Malmo played out a 2-2 draw at home to Greece's PAOK after twice taking the lead and Steaua Bucharest shared a 1-1 draw at Sparta Prague.
Midtjylland beat Hungarians Ferencvaros 2-0 in Denmark, while Azerbaijani side Qarabag lost 2-1 at home to Ludogorets of Bulgaria.
Austrian outfit Red Bull Salzburg and new head coach and former Liverpool assistant Pep Lijnders emerged 2-1 home victors against Netherlands' Twente.
The second leg fixtures will take place on August 13.