Dynamo Kiev celebrated a 2-1 win at 10-man Gent in the first leg of their Champions League playoff tie while Norway's Molde fought back from a two-goal deficit in a thrilling 3-3 home draw with Hungary's Ferencvaros on Wednesday.
Striker Vladyslav Supryaha fired Dynamo into a ninth-minute lead when he tapped the ball in from close range, with the goal awarded after a delayed VAR check showed Vitaliy Buyalskiy was onside when he passed the ball.
The Belgian side levelled in the 41st through substitute Tim Kleindienst, who headed in a corner at the near post after he had replaced the injured Roman Yaremchuk.
Gent's Ukrainian forward Roman Bezus was sent off after committing two bookable fouls shortly after halftime and Dynamo took full advantage as they laid siege to the home team's goal and grabbed a 79th-minute winner.
A deflected shot by substitute Viktor Tsygankov fell kindly for Uruguayan forward Carlos De Pena, who drilled his shot through goalkeeper Davy Roef's legs to put Dynamo in a commanding position to reach the group stage.
Ferencvaros appeared to be cruising after goals from Franck Boli and Myrto Uzuni gave them a 2-0 lead at Molde but they needed a late penalty to avoid defeat after the home side's spirited fightback.
Leke James pulled one back for the Norwegian champions and captain Magnus Wolff Eikrem equalised with a superb volley before defender Martin Ellingsen put them in front with a fine header.
The visitors were awarded a contentious penalty in the 87th minute and Igor Kharatin converted it as he sent goalkeeper Andreas Linde the wrong way to deny Molde victory.
Valbuena fired Olympiakos ahead with a 69th-minute penalty and El Arabi added a late second.
The second legs take place next week.