The Moto3 race was originally due to run over 17 laps, but was red flagged on the fourth tour following an incident between Filippo Farioli and Xabi Zurutuza.
Zurutuza crashed at Turn 9 on lap three and was struck by the bike of Farioli, who was running directly behind. Zurutuza needed trackside medical assistance but was conscious throughout.
Transferred to the medical centre, he was diagnosed with back trauma and is undergoing further checks.
The race was restarted over 11 laps, with championship leader Alonso strengthening his position at the top of the standings.
Alonso led from pole off the line on his Aspar CFMoto and was hounded in the first half of the race, with the likes of Collin Veijer and Taiyo Furusato taking turns heading the field.
Having gotten back into the lead on lap eight, Alonso made a decisive break, though Intact GP’s Veijer managed to close him down over the final tour.
But Alonso held firm for his fifth win of the season, leading Veijer across the line by 0.142 seconds.
Ryusei Yamanaka completed the podium on his MT Helmets – MSI KTM for his first rostrum in Moto3, with Furusato fourth on the Team Asia Honda. David Munoz was fifth for BOE Motorsports.
Ivan Ortola was running in the podium battle on the final lap but crashed at Turn 12. The MT Helmets – MSI rider remounted to finish sixth, with SIC58’s Luca Lunetta seventh.
Adrian Fernandez was eighth for Leopard Honda, with Jacob Roulstone (Tech3 GasGas) and Matteo Bertelle (Snipers Honda) rounded out the top 10.
Title contender Dani Holgado was 14th on his Tech3 GasGas having been forced to serve two long laps for triggering a Turn 1 collision between Jose Antonio Rueda and Stefano Nepa on the opening lap.
Alonso’s championship lead over Holgado has swelled to 37 points, with Veijer 48 adrift in third.
Italian GP — Moto3 race results:
| 1 |
D. Alonso CFMOTO Valresa Aspar Team |
80 | CF MOTO | 11 | 162.5 | 25 | ||||
| 2 |
C. Veijer Liqui Moly Husqvarna Intact GP |
95 | Husqvarna | 11 | 0.142 | 162.5 | 20 | |||
| 3 |  R. Yamanaka MT Helmets — MSI |
6 | KTM | 11 | 1.111 | 162.3 | 16 | |||
| 4 | T. Furusato Honda Team Asia |
72 | Honda | 11 | 0.447 | 162.3 | 13 | |||
| 5 |  D. Munoz BOE Motorsports |
64 | KTM | 11 | 3.699 | 161.8 | 11 | |||
| 6 |
I. Ortola MT Helmets — MSI |
48 | KTM | 11 | 7.157 | 160.9 | 10 | |||
| 7 |
L. Lunetta SIC58 Squadra Corse |
58 | Honda | 11 | 1.283 | 160.8 | 9 | |||
| 8 |  A. Fernandez Leopard Racing |
31 | Honda | 11 | 0.132 | 160.7 | 8 | |||
| 9 |
J. Roulstone Red Bull GASGAS Tech3 |
12 | GASGAS | 11 | 0.128 | 160.7 | 7 | |||
| 10 |  M. Bertelle Kopron Rivacold Snipers Team |
18 | Honda | 11 | 0.007 | 160.7 | 6 | |||
| 11 |
Á. Piqueras Leopard Racing |
36 | Honda | 11 | 0.193 | 160.7 | 5 | |||
| 12 |  J. Kelso BOE Motorsports |
66 | KTM | 11 | 0.036 | 160.7 | 4 | |||
| 13 | R. Rossi CIP |
54 | KTM | 11 | 2.564 | 160.4 | 3 | |||
| 14 | D. Holgado Red Bull GASGAS Tech3 |
96 | GASGAS | 11 | 5.132 | 159.7 | 2 | |||
| 15 |
J. Antonio Red Bull KTM Factory Racing |
99 | KTM | 11 | 0.060 | 159.7 | 1 | |||
| 16 |
N. Fabio LEVELUP — MTA |
10 | KTM | 11 | 0.031 | 159.7 | ||||
| 17 |  S. Ogden MLav Racing |
19 | Honda | 11 | 0.083 | 159.7 | ||||
| 18 |
J. Esteban CFMOTO Valresa Aspar Team |
78 | CF MOTO | 11 | 0.054 | 159.7 | ||||
| 19 |
F. Farioli SIC58 Squadra Corse |
7 | Honda | 11 | 3.397 | 159.3 | ||||
| 20 |
N. Dettwiler CIP |
55 | KTM | 11 | 0.201 | 159.3 | ||||
| 21 |
D. Almansa Kopron Rivacold Snipers Team |
22 | Honda | 11 | 7.776 | 158.3 | ||||
| 22 |
T. Buasri Honda Team Asia |
5 | Honda | 11 | 4.055 | 157.8 | ||||
| 23 | J. Whatley MLav Racing |
70 | Honda | 11 | 15.322 | 156.0 | ||||
| dnf | S. Nepa LEVELUP — MTA |
82 | KTM | 0 | Accident | |||||
| dnf | T. Suzuki Liqui Moly Husqvarna Intact GP |
24 | Husqvarna | 0 | Accident | |||||
| dns |
X. Zurutuza Red Bull KTM Factory Racing |
85 | KTM | 0 | Accident before restart |
Roberts triumphant in Moto2
Due to the red flag stoppage in Moto3, the Moto2 race was shortened to 12 laps and was won by poleman Joe Roberts for American Racing.
The Californian started from pole but had to fight all the way to the chequered flag to score his second grand prix win of his career.
Roberts led for the first three laps before Alonso Lopez overtook him on his Speed Up bike on the fourth tour into Turn 4.
When Roberts went to take the lead back from Lopez at Turn 1 on lap nine, the pair ran wide and allowed Gresini’s Manuel Gonzalez to hit the front.
Roberts then went from third to the lead into Turn 1 on the following tour and resisted an attack from Gonzalez at the same place on the final lap.
The American Racing rider outdragged Gonzalez to the chequered flag by just 0.067 seconds, boosting him to second in the standings and just seven points off the lead.
Lopez completed the podium ahead of the warring MT Helmets – MSI duo of championship leader Sergio Garcia and Ai Ogura.
Aron Canet was sixth on his Fantic Racing machine ahead of Ajo KTM’s Celestino Vietti. Izan Guevara (Aspar), Somkiat Chantra (Honda Team Asia) and Marcos Ramirez (American Racing) rounded out the top 10.
Fermin Aldeguer endured a torrid Mugello weekend, with neck pain forcing him to miss qualifying.
Fighting back into the points in the early stages, the Speed Up rider was taken down in an incident with Jeremy Alcoba on lap four. He is now 59 points down in the championship in sixth.