Championship leader Julian Simon inherited victory in the 125cc San Marino Grand Prix as race leaders Pol Espargaro and Andrea Iannone crashed together on the last lap.
Aspar Aprilia's Simon fought for the lead for most of the race with Ongetta Aprilia's Iannone, with the two opening a gap as wide as 2.6 seconds over the rest of the field.
But Espargaro, who after dropping well out of the top 10 at the start had a great race with several fastest laps and plenty of overtaking moves, joined the leading pair with three laps to go in the 23-lap race and passed them.
An exciting penultimate lap, with Iannone and Espargaro switching many times position at the front, led to the final lap, where the Italian got on the inside of the Spaniard at the last corner, but went too deep, lost control, and swept out the Derbi and its rider.
After both men crashed over the gravel, Espargaro went shouting at Iannone and the latter slightly headbutted the former while the two still had their helmets on.
Simon thus went on to win and increase his lead in the championship, followed by Nicolas Terol (Jack & Jones Aprilia), who took the lead at the start, and a distant Bradley Smith on the second Aspar Aprilia.
Marc Marquez classified fourth with his KTM, ahead of Sandro Cortese's Ajo Derbi and Stefan Bradl's Kiefer Aprilia.
Fontana Aprilia's Simone Corsi was with the leading duo for the first eight laps but then dropped down the order to finish seventh.
Sergio Gadea had a lucky escape when he high-sided his Aspar Aprilia on the first lap. The Spaniard landed in the middle of the track, but thankfully all the riders that followed him managed to avoid him.
Pos Rider Bike Time
1. Julian Simon Aprilia 40m15.301s
2. Nicolas Terol Aprilia + 0.573s
3. Bradley Smith Aprilia + 5.474s
4. Marc Marquez KTM + 9.378s
5. Sandro Cortese Derbi + 9.665s
6. Stefan Bradl Aprilia + 11.755s
7. Simone Corsi Aprilia + 23.044s
8. Joan Olive Derbi + 26.936s
9. Jonas Folger Aprilia + 32.851s
10. Daniel Webb Aprilia + 34.439s
11. Michael Ranseder Aprilia + 34.733s
12. Efren Vazquez Derbi + 35.763s
13. Riccardo Moretti Aprilia + 35.853s
14. Lorenzo Zanetti Aprilia + 39.937s
15. D.Agerter Derbi + 39.942s
16. Johann Zarco Aprilia + 40.110s
17. R.Krummenacher Aprilia + 59.051s
18. Lukas Sembera Aprilia + 59.100s
19. Luigi Morciano Aprilia +1m00.236s
20. Takaaki Nakagami Aprilia +1m01.191s
21. Luis Salom Aprilia +1m02.848s
22. Cameron Beaubier KTM +1m11.814s
23. Jasper Iwema Honda +1m11.933s
24. Luca Marconi Aprilia +1m12.053s
25. Gabriele Ferro Aprilia +1m14.596s
26. Jakub Jantulik Aprilia +1m28.731s
27. Luca Vitali Aprilia +1m29.309s
28. Jakub Kornfeil Loncin +1m29.916s
29. A.Tonucci Aprilia + 1 Lap
Rider Bike On lap
Andrea Iannone Aprilia 22
Pol Espargaro Derbi 22
Tomoyoshi Koyama Loncin 16
Esteve Rabat Aprilia 15
Lorenzo Savadori Aprilia 13
Scott Redding Aprilia 5
Sergio Gadea Aprilia 0
FASTEST LAP: Espargaro, 1m43.613s on lap 20