Reigning Michelin Le Mans Cup champion Laurents Horr was joined by 17-year-old French driver Mathieu de Barbuat, who was making his ELMS debut in Monza in only his second ever race in a car.
The no4 Duqueine took the chequered flag 21 seconds ahead of the no2 United Autosports Ligier of reigning champion Wayne Boyd, with the no13 Inter Europol Competition Ligier taking the final podium position 26 seconds behind the second placed car.
- Mathieu de Barbuat was at the head of the LMP3 grid at the start of the 4 Hours of Monza but was passed by the no13 Inter Europol Competition Ligier of Martin Hippe at the start.
- The no9 Graff Ligier of Rory Pentinnen spun at Ascari on the opening lap with a rear left puncture. The Finn was able to recover the car to the pits, but the bodywork damage incurred by the flailing rubber meant a longer than usual stop to repair.
- The top three cars – no13 Ligier, no4 Duqueine and no2 Ligier (Rob Wheldon) were fighting for the lead and, like the LMP2 front runners, were split by less than a second for several laps.
- De Barbuat held of the challenge from 2020 LMP3 champion Rob Wheldon until lap 11 when the British driver got past to claim second spot a T3.
- The race leader Martin Hippe then had the no2 Ligier filling his mirrors for the next 20 minutes before the Safety Car was deployed to recover the no77 Porsche that was beached in the gravel at T7.
