Celta Vigo recovered from an early deficit to claim a 3-2 win from the first leg of their Europa League quarterfinal against Genk at Balaidos.
The Belgian visitors took a 10th-minute lead through Jean-Paul Boetius' header but Celta hit back in emphatic fashion and were ahead inside seven minutes thanks to goals from Pione Sisto and Iago Aspas.
John Guidetti added a third before the break as Celta threatened to sweep aside their opponents, but veteran Genk playmaker Thomas Buffel pulled a goal back to leave the tie evenly balanced heading into next week's second leg.
Celta are looking to reach the semifinals of European competition for the first time in their history but their hopes suffered an early setback as Genk took the lead.
Leandro Trossard did well to collect an over-hit cross from the right, create space for himself and then deliver a perfect ball back into the box that Boetius headed past Sergio Alvarez.
Having seen their side beaten 2-0 by Eibar in their last home outing, Celta fans might have feared the worst at that point, but Eduardo Berizzo's men roared back in style.
They equalised four minutes later with a superbly-worked team goal that was clinically finished off by Sisto, who picked up a clever flick by Guidetti before curling a shot past Matthew Ryan and into the roof of the net.
Three minutes after that and Celta were ahead with Aspas, almost inevitably, getting on the scoresheet.
The Spain international capitalised on a poor clearance to race towards the edge of the Genk box and drill home his 23rd goal of the season in all competitions.
Celta made it 3-1 in the 38th minute when Guidetti fired home low into the near corner of Ryan's net, and at half-time things were looking rosy for the Spanish side.
However, Genk survived a couple of escapes at the start of the second half and then pulled a goal back in the 68th minute when 36-year-old Buffel headed home at the second attempt following a defensive misjudgement by Jonny Castro.
Celta pushed for a fourth goal late on but Gustavo Cabral and Aspas could not make the most of their chances.