Daniel Ricciardo claimed McLaren's first victory in almost nine years at the Italian Grand Prix, a race that saw title contenders Max Verstappen and Lewis Hamilton collide and crash out of the race.
It was Ricciardo's first win since 2018 and McLaren's first since the 2012 Brazilian Grand Prix.
Teammate Lando Norris finished second ahead of Mercedes' Valtteri Bottas, McLaren's first one-two finish since the 2010 Canadian Grand Prix.
Ricciardo, who had struggled for form since joining McLaren this year, said on the radio after the race: "Deep down I knew this was going to come. So thanks, thanks for having my back.
"And for anyone who thought I left ... I never left. Just moved aside for a while! Thanks guys."
Ricciardo had snatched the initiative at the start, beating Verstappen on the run down to Turn 1. He dictated the race from that point on and would likely have won regardless of what had happened between the championship rivals.
A slow pit stop from Verstappen seemed to move him out of contention for the lead and back toward Hamilton, who had spent the first spell of the race stuck behind Norris.
The key moment came on Lap 27, after Hamilton had made his pit stop a few laps after Verstappen's. When Hamilton emerged from the pit lane, he was just in front of Verstappen as they drove down toward the Turn 1 chicane.
Hamilton kept the inside line for the right-hander and then as they turned left, the pair collided, with Verstappen's car bouncing over the top of the Mercedes and coming to a rest on top of it in the gravel trap.
Verstappen was furious and stormed from the scene of the accident back to the garage without talking to his title rival.
That incident prompted a safety car period. When the race resumed, Ricciardo held the lead from McLaren teammate Lando Norris.
Norris radioed McLaren at one point to suggest the team swap positions, as Ricciardo was driving too slowly, but the Australian driver was flawless throughout.
It is the eighth win of Ricciardo's career and his first since the 2018 Monaco Grand Prix, which he won for Red Bull.
Charles Leclerc finished fourth for Ferrari at the team's home race ahead of Sergio Perez.
Perez actually crossed the line in third position, but dropped two positions down the order after having incurred a five-second penalty for using the chicane to gain an advantage in a battle with Bottas.