Marc Marquez finished second after being unable to catch the #1 Ducati despite a late charge, with Pedro Acosta also on the podium.
It was a lightning start for Bagnaia (Ducati Team), passing pole-sitter Martin (Pramac Ducati) to take the holeshot into San Donato.
Both Red Bull KTMs were also significant movers early on as Jack Miller and team-mate Brad Binder gained six and eight places to complete the first lap in 13th and fifth respectively.
As early as the second lap, the attrition was to start after Miguel Oliveira (Trackhouse Racing Aprilia) tried to turn inside Fabio Quartararo (Monster Energy Yamaha), only to lose the front and cause them both to crash out.
Stewards reviewed the clash but deemed it a racing incident, as they did for the next drama at Turn 1.
On Lap 3, Enea Bastianini (Ducati Team) had entered too hot trying to out-brake Martin.
The Spaniard took the inside line to make the pass only for Bastianini to attempt the cut-back where he made contact with the Pramac bike and crashed.
Bagnaia consolidated his lead over the next couple of laps to over a second by the half-race stage.
Seeing his chance of a win slipping away, third placed Marc Marquez increased his pace and worked his way past Martin for second place on Lap 6, with five laps remaining to catch Bagnaia.
Acosta was circulating in fourth place at that point, ahead of the in-form Franco Morbidelli (Pramac Ducati) and Binder. He would slowly break his way from this pair to a relatively lonely fourth place.
Martin is a regular on Sprint race podiums but the championship leader became another casualty of the first turn, losing the front on the eighth lap.
To make matters worse for Martin, his biggest rivals this season made the most of his first Sprint DNF. Bagnaia was clear in front, Marquez was gifted second place, and Acosta moved into third place.
Marquez had the final three laps to catch a deficit of 1.2s to upset Bagnaia.
Stronger in the first half of the lap, Marquez was able to decrease the deficit to 0.8s before Bagnaia responded with a strong finish to take the chequered flag 1.469 seconds ahead.
Acosta was 2.7s behind in a safe third place while Miller did also see the finish line, only gained one further position after the start with a late overtake on Alex Rins (Monster Energy Yamaha) to take 12th.
Martin enters the weekend’s Italian Grand Prix race with only a 27-point lead over Bagnaia and 32 over Marquez.
The 23-lap race is scheduled to commence at 22:00 AEST.
Race results: Sprint race
Pos | Num | Rider | Nat | Team | Bike | Time/Gap |
1 | 1 | F. Bagnaia | ITA | Ducati Lenovo Team | Ducati | 19:30.251 |
2 | 93 | M. Marquez | ESP | Gresini Racing MotoGP | Ducati | +1.469 |
3 | 31 | P. Acosta | ESP | Red Bull GASGAS Tech3 | KTM | +4.147 |
4 | 21 | F. Morbidelli | ITA | Prima Pramac Racing | Ducati | +5.421 |
5 | 12 | M. Viñales | ESP | Aprilia Racing | Aprilia | +7.693 |
6 | 33 | B. Binder | RSA | Red Bull KTM Factory Racing | KTM | +8.271 |
7 | 49 | F. Di Giannantonio | ITA | Pertamina Enduro VR46 Racing Team | Ducati | +8.571 |
8 | 73 | A. Marquez | ESP | Gresini Racing MotoGP | Ducati | +8.846 |
9 | 41 | A. Espargaro | ESP | Aprilia Racing | Aprilia | +8.984 |
10 | 25 | R. Fernandez | ESP | Trackhouse Racing | Aprilia | +10.085 |
11 | 72 | M. Bezzecchi | ITA | Pertamina Enduro VR46 Racing Team | Ducati | +10.199 |
12 | 43 | J. Miller | AUS | Red Bull KTM Factory Racing | KTM | +13.988 |
13 | 42 | A. Rins | ESP | Monster Energy Yamaha MotoGP Team | Yamaha | +14.137 |
14 | 44 | P. Espargaro | ESP | Red Bull KTM Factory Racing | KTM | +18.259 |
15 | 5 | J. Zarco | FRA | CASTROL Honda LCR | Honda | +18.309 |
16 | 30 | T. Nakagami | JPN | IDEMITSU Honda LCR | Honda | +19.374 |
17 | 37 | A. Fernandez | ESP | Red Bull GASGAS Tech3 | KTM | +23.060 |
18 | 32 | L. Savadori | ITA | Aprilia Racing | Aprilia | +24.596 |
19 | 10 | L. Marini | ITA | Repsol Honda Team | Honda | +25.587 |
DNF | 89 | J. Martin | ESP | Prima Pramac Racing | Ducati | 7 laps |
DNF | 36 | J. Mir | ESP | Repsol Honda Team | Honda | 4 laps |
DNF | 23 | E. Bastianini | ITA | Ducati Lenovo Team | Ducati | 2 laps |
DNF | 88 | M. Oliveira | POR | Trackhouse Racing | Aprilia | 1 laps |
DNF | 20 | F. Quartararo | FRA | Monster Energy Yamaha MotoGP Team | Yamaha | 1 laps |
Race winner: 11 laps
Riders’ championship
Pos | Rider | Nat | Pts |
1 | J. Martin | ESP | 155 |
2 | F. Bagnaia | ITA | 128 |
3 | M. Marquez | ESP | 123 |
4 | E. Bastianini | ITA | 94 |
5 | M. Viñales | ESP | 92 |
6 | P. Acosta | ESP | 90 |
7 | B. Binder | RSA | 79 |
8 | A. Espargaro | ESP | 77 |
9 | F. Di Giannantonio | ITA | 65 |
10 | A. Marquez | ESP | 44 |
11 | M. Bezzecchi | ITA | 42 |
12 | F. Quartararo | FRA | 32 |
13 | M. Oliveira | POR | 29 |
14 | R. Fernandez | ESP | 28 |
15 | J. Miller | AUS | 27 |
16 | F. Morbidelli | ITA | 21 |
17 | A. Fernandez | ESP | 13 |
18 | J. Mir | ESP | 13 |
19 | J. Zarco | FRA | 9 |
20 | T. Nakagami | JPB | 8 |
21 | A. Rins | ESP | 7 |
22 | D. Pedrosa | ESP | 7 |
23 | P. Espargaro | ESP | 0 |
24 | L. Marini | ITA | 0 |
25 | S. Bradl | GER | 0 |
26 | L. Savadori | ITA | 0 |