Brad Binder won MotoGP's sprint race in Argentina after a stunning ride saw him surge from 15th on the grid.
The South African beat Marco Bezzecchi by just 0.072 seconds, with his Mooney VR46 team-mate Luca Marini coming in third to clinch a double podium for the team.
Binder enjoyed a meteoric rise through the pack on the opening lap, leaping from his lowly start position to fourth and taking the lead on lap three en route to victory.
Prior to the sprint, Marquez secured pole after a dramatic day for the Spaniard in Q1 saw him go top, crash out and abandon his number one bike as it caught fire.
The younger Marquez brother rallied in Q2 after gambling on slick tyres in wet conditions to seal a maiden pole and his spot at the front of the pack for Sunday's race, following in his brother's footsteps after his pole in the season opener.
Bezzecchi, who starts second, smashed the top time by two seconds but Marquez pipped him to pole, while a late charge from Francesco Bagnaia saw him bump Franco Morbidelli out of the top three.
Binder's victory in the sprint caused quite a stir, with the man himself among those surprised by his performance.
"I didn't expect that at all, honestly my bike worked so well from the first lap and I got the most unreal start I could have ever asked for," he told reporters.
"I got really lucky [at the start] where there was a gap where the riders split, some were on the left and some were right so I could get down the middle and just chip my way through.
"I couldn't have ever dreamed of getting a start that good, so when I saw an opportunity of getting to first I took it with both hands and from then on it was a case of whoever passed me try and divebomb them straight back.
"We made a huge step from [Friday] and I was able to keep rhythm at my fastest lap from [Friday], so hats off to the team. They did an unreal job.
"My rhythm wasn't terrible, and even though the other guys had a bit extra at the end we won the race so I can't complain and I'm really happy."
GRID CLASSIFICATION
1. Alex Marquez (Gresini) 1:43.881
2. Marco Bezzecchi (Mooney VR46) +0.172
3. Francesco Bagnaia (Ducati) +0.858
4. Franco Morbidelli (Monster Energy Yamaha) +2.101
5. Maverick Vinales (Aprilia) +2.355
6. Johann Zarco (Pramac Racing) +2.582
7. Luca Marini (Mooney VR46) +2.707
8. Jorge Martin (Pramac Racing) +2.754
9. Aleix Espargaro (Aprilia) +2.997
10. Fabio Quartararo (Monster Energy Yamaha) +3.241
SPRINT RESULT
1. Brad Binder (Red Bull KTM) 19:56:873
2. Marco Bezzecchi (Mooney VR46) +0.072
3. Luca Marini (Mooney VR46) +0.877
4. Franco Morbidelli (Monster Energy Yamaha) +2.354
5. Alex Marquez (Gresini) +2.462
6. Francesco Bagnaia (Ducati) +2.537
7. Maverick Vinales (Aprilia) +2.643
8. Jorge Martin (Pramac Racing) +3.754
9. Fabio Quartararo (Monster Energy Yamaha) +4.856
10. Jack Miller (Red Bull KTM) +5.143
CHAMPIONSHIP STANDINGS
1. Francesco Bagnaia (Ducati) 41
2. Maverick Vinales (Aprilia) 28
3. Marco Bezzecchi (Mooney VR46) 25
4. Brad Binder (Red Bull KTM) 22
5. Alex Marquez (Gresini) 17
6. Johann Zarco (Pramac Racing) 15
7. Jack Miller (Red Bull KTM) 15
8. Jorge Martin (Pramac Racing) 11
9. Aleix Espargaro (Aprilia) 11
10. Fabio Quartararo (Monster Energy Yamaha) 9