Derry City deservedly came from behind to defeat Finnish side KuPS Kuopio 2-1 at a packed Ryan McBride Brandywell Stadium.
Trailing to Axei Vidjeskog's penalty, second-half goals from Will Patching and Cian Kavanagh secured the memorable European success.
The Candystripes, who deserved to win by a bigger margin, will travel to Finland for next week's second-leg encounter confident that they can continue their Europa Conference League adventure into the third qualifying round.
The visitors went close in the opening minutes when Axei Vidjeskog's close range header at the back post was blocked on the line by City centre-back Mark Connolly. City created an opening on 14 minutes but Ben Doherty's 20-yard strike, which was well hit, was saved at the second attempt by KuPS goalkeeper Johannes Kreidl.
The combination of woodwork and Kreidl denied Derry taking the lead moments later as Patrick McEleney's lovely pass found Ronan Boyce inside the box, but the right-back's attempted chip was tipped onto the bar by the KuPS keeper.
On 21 minutes Boyce went close again, this time his looping header, at the back post from Brandon Kavanagh's left wing cross, clipped the crossbar before sailing over. The visitors were rightfully awarded a penalty right on the stroke of half-time after Mark Connolly had handled Urho Nissilä's goalbound shot inside the box. Referee Robertas Valikonis pointed to the spot and Vidjeskog made no mistake from 12 yards, slotting the ball low into Brian Maher's bottom left hand corner.
Derry boss Ruaidhri Higgins would have wanted a response from his players in the second half and they went close to levelling on 52 minutes but Brandon Kavanagh's curling right footed strike was well saved by Kreidi.
On 60 minutes a clever pass by Michael Duffy released Jamie McGonigle, but the striker's left footed shot from just inside the box was comfortably saved by Kreidl. KuPS were inches away from doubling their lead moments later as Tete Yengi's well hit drive from the edge of the box was superbly kept out by a full stretched Maher.
Derry deservedly drew level on 69 minutes as substitute Paul McMullan picked out WIll Patching inside the box and the big midfielder's close range header found Kreidl's bottom right hand corner, despite the keeper's best attempts at trying to keep it out.
With their tails up the home side went close taking the lead as substitute Cian Kavanagh saw his shot saved by a diving Kreidl and Duffy's close range effort was blocked on the line by Seth Saarinen.
The Candystripes took the lead on 79 minutes as Duffy's left wing centre across the six yard box found an unmarked Kavanagh, who gleefully fired home.
Kavanagh should have done better on 90 minutes, but he headed over from close range, after McMullan's right wing cross had picked him out.
In stoppage time Kreidl had to make a big save to keep the scoreline down, as he denied substitute Adam O'Reilly, after the midfielder had burst into the KuPS penalty box to get his shot away.
From Ben Doherty's resulting right-wing corner Kreidl somehow kept out Kavanagh's close range header.
Derry City: Brian Maher, Ronan Boyce, Mark Connolly, Cameron McJannet, Ben Doherty; Cameron Dummigan, Patrick McEleney (Sadou Diallo 83), Will Patching (Adam O'Reilly 83); Michael Duffy, Jamie McGonigle (Cian Kavanagh 71), Brandon Kavanagh (Paul McMullan 62).
KuPS Kuopio: Johannes Kreidl, Tony Miettinen, Taneli Hämäläinen, Henri Toivomäki, Seth Saarinen, Urho Nissilä (Arttu Heinonen 87), Jaakko Oksanen, Axel Vidjeskog (Gabriel Bispo 73), Jasse Tuominen (Pyry Laminen 68), Tete Yengi, Saku Savolainen (Jake Jervis 68). Subs: Dahlstorm, Gabriel, Heinonen, Jervis, Lampinen, Miettinen, Pitkanen, Riihimaki.
Referee: Mr Robertas Valikonis (Lithuania).
