Wisła Kraków will take a narrow lead into next week's second leg after Maor Melikson's strike earned the Polish champions a 2-1 win against PFC Litex Lovech.
Michael Lamey gave the visitors the perfect start inside 20 minutes when he raced clear of the Litex defence and lobbed goalkeeper Vinícius. The hosts responded in first-half added time through Wellington, but Melikson struck with 14 minutes remaining to give Robert Maaskant's side the upper hand in the tie.
The hosts started the better of the two teams and almost forged ahead inside the opening ten minutes, Hristo Yanev's delightful free-kick coming back off the crossbar. Luboslav Penev's charges failed to make the most of their early dominance and paid the price on 19 minutes as Lamey beat the offside trap and finished over Vinícius.
Litex fought back and came close to levelling the scores six minutes before the break, only for Georgi Milanov to fire his shot narrowly wide. With just seconds remaining in the opening period, however, the Bulgarian champions got the equaliser their first-half performance merited. Svetoslav Todorov, so often at the heart of Litex's fluent attacking play, released Wellington, whose clinical finish gave Milan Jovanić no chance in the visitors' goal.
Picking up where they left off after the break, Litex were unfortunate not to take the lead, Wellington testing the reflexes of Jovanić. As they pushed forward in search of a winner, though, Wisła hit them on the break with Melikson's low strike from just outside the area too good for Jovanić. Litex piled men forward late on looking for an equaliser but Nikolay Bodurov could only graze the bar with his header.