Zenit St Petersburg and Porto took the advantage in the first leg of their Champions League qualifying ties as they both claimed away wins on Wednesday night.
Zenit overcame Belgian side Standard Liege 1-0 at the Stade Maurice Dufrasne thanks to Oleg Shatov's 16th-minute score while Porto defeated Lille by the same scoreline in France as a result of Hector Herrera's 61st minute goal.
Celtic appear to have taken advantage of their European reprieve with a well-deserved 1-1 draw against Maribor in the first leg of their play-off in Slovenia.
Callum McGregor shot the visitors into the lead in the sixth minute, only to see his fourth goal in seven games cancelled out by Damjan Bohar.
AaB also drew 1-1 against Apoel Nicosia after Nicolaj Thomsen's 16th-minute goal was cancelled out by Franco Vinicius early in the second half.
Slovan Bratislava and BATE were also tied after the first leg, although BATE had the away goal advantage thanks to Tomas Jablonsky's 44th-minute own goal, with substitute Robert Vittek keeping Slovan in the tie with an 80th-minute leveller.