Abarth 695 Assetto Corse Evolution driver Lilja took the chequered flag ahead of Italian duo Manuel Buffoli and Campani.
Campani's lead at the top of the standings with one race remaining this season is now just six points. He has already won the 2014 National Trophy ACI / CSAI Abarth Selenia Italy.
The title will now be decided in race two at the Italian track, the final race of the season.
Trofeo Abarth
Campani seals title in thrilling fashion at Monza
15/11/2014 AT 00:40
In the first outing of the weekend, Lilja started perfectly from the pole, followed by Campani and Buffoli.
Luca Anselmi soon joined that trio and on the seventh lap Buffoli overtook Campani, at which stage just over two tenths of a second separated the four cars.
Buffoli's ascendance continued as he took the lead but he span out at the Roggia, setting up a thrilling duel between Campani and Lilja.
Buffoli managed to claw his way back into contention though and on lap 11 he took over the lead, only for Lilja to react quickly and overtake him once more.
From that position, the Swede never looked back and he went on to claim a victory that will send the title race to the very last.
Luca Anselmi came in fourth, with Eric Scalvini in fifth and Piero Longhi sixth.
For Longhi the race was a throwback to the single-make Abarth trophies after 23 years' absence - he won the Fiat Uno Turbo rally Championship in 1990.
Among the Abarth 500 Assetto Corse, young Finn Jusso Pajuranta won the class after hard-fought battle. After a continuous exchange of positions Pajuranta emerged victorious ahead of Swede Robin Appelqvist and Franco Cimarelli.
This success allows Pajuranta to acquire the Italian title of that challenge, the Finn having already conquered the European one before Monza.
Race one result:
1. Niklas Lilja, 13 giri in 28’48”231, average speed 156,872 km/h;
2. Manuel Buffoli +0”284;
3. Alex Campani +0”491;
3. Manuel Buffoli +1”327;
4. Luca Anselmi +0”767;
6. Eric Scalvini +12”344;
6. Piero Longhi +12”886;
7. “Fischerman” +28”538;
8. Santosh Berggren +43”054;
9. Juuso Pajuranta (Abarth 500 Assetto Corse) +52”155;
10. Robin Appelqvist (Abarth 500 Assetto Corse) +53”346.
Trofeo Abarth
Lilja grabs pole at Monza
26/10/2014 AT 10:08
Trofeo Abarth
Double delight for Campani in Sicily
30/09/2014 AT 00:11