Celtic are facing the prospect of missing out on qualifying for the UEFA Champions League group stages after a heavy defeat in their third qualifying round first-leg encounter against Legia Warsaw.
Ronny Deila's 10-man side fell to a 4-1 defeat in the Polish capital, although the match started brightly for the Hoops when Callum McGregor scored the opening goal of the game in the eighth minute.
That is as good as it got for the Scottish champions as Miroslav Radovic equalised for the hosts two minutes later and then put his side in front with nine minutes of the first half remaining before Efe Ambrose was sent off just before the interval.
Radovic then turned provider, teeing up Michal Zyro, who slotted home with six minutes of the game left and Jakub Kosecki then found the back of the net in added time to really rub salt in their opponents' wounds. The margin of defeat could have been far greater had Ivica Vrdoljak not missed two second-half penalties.
Lille took a step towards qualifying for the group stages by winning 2-0 against Grasshopper in Zurich.
Rene Girard's side took the lead at the Stadion Letzigrund in the 29th minute when Sebastien Corchia found himself unmarked at the far post to slot home a Ryan Mendes cross from the left wing. Corchia returned the favour four minutes after the half-time break and Mendes made no mistake from close range to double Lille's lead.
Andre Villas-Boas' Zenit St Petersburg have it all to do in the second leg after they lost 1-0 to Cypriot side AEL Limassol in Larnaca.
Lukasz Gikiewicz's 64th-minute goal was enough to secure victory for the hosts, while Zenit's miserable night was compounded by Axel Witsel's second-half sending-off.
Red Bull Salzburg also had an away day to forget as they slumped to a 2-1 defeat to Azeri side Qarabag FK in Baku.
Danilo Dias gave the hosts the perfect start when he opened the scoring in the second minute, before Jonathan Soriano equalised for Salzburg in the 77th minute.
The majority of those watching at the Tofiq Bahramov Stadium were delirious with excitement nine minutes later when Reynaldo dos Santos Silva scored what proved to be the winner with four minutes to play.
Turkish side Besiktas had better luck on their travels, however, with goals from Mustafa Pektemek and Kerim Frei earning a 2-1 victory at Feyenoord. Mitchell te Vrede notched a consolation strike five minutes into added time for the hosts.
Dinamo Zagreb joined Besiktas in triumphing away from home as a Marcelo Brozovic strike four minutes into the second half proved to be the only goal of the game against Danish outfit Aalborg BK.
Maccabi Tel Aviv's game at Solvenian side NK Maribor was heading toward a stalemate until Damjan Bohar scored the winner in the fifth minute of added time to secure a 1-0 victory for the hosts.
Steaua Bucherest were forced to settle for a 2-2 draw at Kazahk side FC Aktobe despite twice taking the lead, while the game between HJK Helsinki and Apoel Nicosia finished with the same scoreline.
Elsewhere, Standard Liege were held to a goalless draw at home to Panathinaikos, Partizan Belgrade achieved the same scoreline at Bulgarian side PFC Ludogorets Razgrad and there were no goals in the game between Dnipro Dnipropetrovsk and FC Copenhagen in Ukraine.