Former European champions Ajax Amsetrdam were held to a 2-2 draw at PAOK in the first leg of their Champions League third qualifying round tie while Red Star Belgrade could only manage a 1-1 home draw against FC Copenhagen on Tuesday.
Azeri champions Qarabag took a big step towards the playoff round with a 2-1 win at Cypriot side APOEL but Dinamo Zagreb left their progress hanging in the balance after the Croats played out a 1-1 home draw against Hungary's Ferencvaros.
A Hans Vaneken penalty late in the first half gave Bruges a 1-0 home win against Dynamo Kiev.
Last season's semi-finalists Ajax, who have won Europe's premier club competition four times, made a perfect start in the cauldron of PAOK's Tumba stadium when Hakim Ziyech curled in a swerving free kick after 10 minutes.
Roared on by a fervent home crowd, PAOK turned the tide before halftime when striker Chuba Akpom capped a flowing move with a fine finish from 10 metres and defender Leo Matos headed home a Diego Biseswar free kick.
Ajax, who suffered a last-gasp defeat by Tottenham Hotspur in last season's semis, piled on the pressure after the break and Ziyech missed a glaring chance before substitute Klaas Jan Huntelaar equalised with a bizarre goal on the hour.
Fernando Varela's poor clearance from Donny van de Beek's cross rebounded off the 35-year old striker's feet into the back of the net from close range and the visitors then dominated until the final whistle.
Red Star, the 1991 champions, conceded a late equaliser after their striker Milan Pavkov reaffirmed his reputation for scoring in big games just before the break, only to be forced off the pitch at halftime by a recurring hamstring injury.
Pavkov, who netted twice in last season's memorable 2-0 home win over eventual Champions League winners Liverpool in the group stage, fired Red Star ahead in the 44th minute when he hooked a loose ball over keeper Sten Michael Grytebust.
Pavkov made way for Richmond Boakye and the hosts were punished in the closing stages for the Ghanaian's forward's second-half profligacy.
Boakye missed a pair of gilt-edged chances to double Red Star's lead before midfielder Dusan Jovancic fouled Copenhagen substitute Mas Jaume in the penalty area and Jonas Wind coolly converted the 84th-minute spot kick.
Dinamo's Spanish midfielder Dani Olmo fired them ahead with a superb goal in the seventh minute as he took a clever back-heel by Mislav Orsic in his stride, nutmegged a defender and hit the far corner of the net with a crisp shot.
But Ferencvaros levelled against the run of play on the hour when David Siger beat Dominik Livakovic with a looping header after the keeper had parried a shot from 10 metres.
Goals from Mahir Emreli and Magaye Gueye gave Qarabag a 2-0 lead at APOEL before Giorgos Merkis pulled one back for the home sides in the 90th minute.
In Wednesday's standout fixtures, 1967 European Cup winners Celtic visit Romania's CFR Cluj while twice former champions Porto are away to Russians Krasnodar.