Slovakia claimed only their third ever major tournament win thanks to Milan Škriniar’s instinctive finish against Poland in Saint Petersburg.
Ondrej Duda had already gone close when Slovakia broke the deadlock 18 minutes in. Róbert Mak did the legwork, slaloming in from the left before unleashing a shot that took one deflection, struck a post and ricocheted in off Wojciech Szczęsny.
There was nothing quite so fortunate about Poland's equaliser just 30 seconds after the interval, Karol Linetty turning the ball in after a neat interchange down the left channel.
Linetty had half a chance to complete the turnaround moments later, but Poland's momentum was checked when Grzegorz Krychowiak was sent off for a second yellow card midway through the second half.
Škriniar, up for a corner, then applied the decisive blow after a sharp turn and finish inside a crowded penalty area, even if Robert Lewandowski, Jan Bednarek and Karol Świderski did all threaten late on.
Star of the Match: Milan Škriniar (Slovakia)
"Scorer of the second goal and a warrior defensively. He was spirited from the first minute to the last. Showed off his strengths by leading the defence and scored the decisive goal."
Jean-François Domergue, UEFA Technical Observer
Rastislav Hríbik, Slovakia reporter
A deserved win, and only Slovakia's second EURO victory ever. Štefan Tarkovič's squad produced a brilliant first half, and they bounced back well from Linetty's equaliser. Krychowiak's red card certainly helped a young side, but it was nonetheless an impressive start.
Piotr Koźmiński, Poland reporter
A very disappointing result for Poland. Paulo Sousa's team struggled in defence and were not able to feed Lewandowski as much as they would have liked. Krychowiak's red card was a turning point, ruining their attacking plans. There's a lot of improvement needed before facing Spain next time out.
Marek Hamšík, Slovakia captain: "It's unbelievable, it's hard to describe. Few people expected us to take the victory today, but we went for it."
Milan Škriniar, Slovakia match winner: "We're delighted to start the competition with a win. It was a difficult game, Poland are a quality team."
Štefan Tarkovič, Slovakia coach: "We were able to keep Lewandowski out of the match. The first half was great. We were asleep for a while at the start of the second half, but we managed to score again and survive the closing minutes."
Paulo Sousa, Poland coach: "The idea was to be the protagonist with the ball and create chances, and we did that. We could do better, yes. We need to be better and show more courage, especially in our back line."