Paris Saint-Germain looked unstoppable in the first half of Wednesday’s Champions League semifinal first leg against Manchester City.

If only the game ended there and then.

PSG surrendered the lead – and control of the tie – to City in the final 45 minutes, losing the contest 2-1 after goals from Kevin De Bruyne and Riyad Mahrez. Idrissa Gueye’s red card in the 77th minute sealed an extraordinary second-half collapse.

PSG jumped ahead in the 15th minute when captain Marquinhos sprinted to head home Angel Di Maria’s inch-perfect corner kick. Midfielders Leandro Paredes and Marco Verratti showed poise under pressure, managing the game while Neymar and Di Maria wreaked havoc in and around the penalty area. City began resorting to tactical fouls just to stem the tide, with PSG firing nine of their 10 shots before halftime.

But City emerged from the dugout as the fresher side, suffocating PSG with a high press that eventually paid dividends. The breakthrough came in the 64th minute when De Bruyne curled a teasing ball into the area that caught goalkeeper Keylor Navas flat-footed. It was a rare error from one of PSG’s standout players in the Champions League this season.

Another mistake cost PSG seven minutes later. Gueye conceded a free-kick just outside of the 18-yard box, and Mahrez blasted home after finding a seam in Navas’ wall.

Gueye then received his marching orders for a reckless studs-up challenge on Ilkay Gundogan, leaving PSG down a man and without a way back into the game.

City can progress to their first Champions League final with a win or draw of any kind in next Tuesday’s second leg at the Etihad.