Zilina is on course to qualify for the group stage of the Champions League for the first time after winning 2-0 at Sparta Prague on Tuesday following second-half goals from strikers Momodou Ceesay and Tomas Oravec.
Ceesay's right-footed shot from inside the area hit the back of the net following a Sparta defensive blunder in the 51st minute.
Oravec headed in the second goal in the 73rd off a corner by Patrik Mraz.
The second leg in Zilina is scheduled for Aug. 25.
''We had a number of scoring opportunities and it was crucial that we converted two of them,'' Zilina coach Pavel Hapal said. ''In the second half, we focused on attack and deserved to win.''
Sparta forward Leonard Kweuke squandered a clear chance in the 12th minute with only the goalkeeper to beat.
Sparta badly missed three suspended players: midfielders Libor Sionko and Marek Matejovsky and striker Bony Wilfried.
''We couldn't field the ideal lineup but still, our performance should have been better,'' Sparta coach Jozef Chovanec said. ''We made terrible mistakes.''
Sparta, once a regular in the Champions League, last played in the group stage five years ago.
Ceesay fired a powerful long-range attempt just wide of Sparta goal in the 62nd.
Oravec had another header saved by goalkeeper Jaromir Blazek when left unmarked in the area, and teammate Robert Jez came close to scoring when he hit a post from a free kick.
