The goal arrived in the tenth minute. Trying to build from the back, Donnarumma misplaced a pass straight to Olise, who needed no second invitation to pounce on the gift.
The Frenchman drove into the penalty area before slotting it home, handing the visitors an early lead.
It was a horror moment for Donnarumma. Italy's captain had gift-wrapped an easy chance for his opponent at the start of a big night on the European stage.
His young team-mate Francesco Pio Esposito hit back, though, levelling for Italy in the 26th minute after winger Niccolo Cambiaghi fizzed a cross across the face of goal to make it 1-1.
Olise, for his part, kept up his outstanding run with France. He has become one of the sharpest attacking weapons in Zinedine Zidane's side, a player who makes the difference with his dribbling, passing and shooting, and whose goal tally keeps climbing.
The former Crystal Palace star scooped the award for best player in the German league in 2025-2026, and topped the chart for goal creators with 21 assists. Add his contributions in the Champions League and he ranks among the finest playmakers on the planet.
His impact ran beyond club level, too. Olise became a key man for France at the 2026 World Cup, where Les Bleus reached the semi-finals and he equalled the record for assists in a single edition by setting up 7 goals.
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This clash with Italy lands at a crucial moment for France, who went into the round top of Group One in the first tier on 10 points after three wins and a draw from four games. Italy sit third on 7.
The first leg, played on 2 October, finished 1-1. Olise put France ahead on home soil in the 55th minute before Alessandro Bastoni levelled for Italy in the 68th.
France want to confirm their superiority and wrap up top spot. Italy, meanwhile, are counting on home advantage and their crowd to grab the win, close the gap and set up the final round of the group stage.
Belgium made Italy's task harder on Thursday by beating Turkey on their own turf 2-1 to snatch second place in the group on 9 points, before hosting the Azzurri in the final round of the UEFA Nations League group stage.
Qualification rules send the top two from each group through to the quarter-finals, turning the France-Italy meeting into a straight scrap for top spot and survival in the tournament.