Julian Simon looked set to leave Estoril on the brink of winning the 2009 125cc World Championship - until he crashed from the lead with seven laps of Sunday's Portuguese Grand Prix remaining.
Simon began the race 57.5 points ahead of nearest rival Nicolas Terol and 62.5 points ahead of team-mate Bradley Smith - and the chance to wrap up his first world title with three rounds to go became a reality when Smith and Terol collided on lap seven.
Race leader Smith had run wide into a 180 degree turn six, forcing him to tip-toe around the edge of the track. The chasing pack promptly swamped him on the exit, but Terol was unsighted and clipped the back of the Englishman's Aspar Aprilia, sending the Jack & Jones Aprilia rider spinning across the track.
Terol rejoined at the back of the field, and soon retired, while Smith finished the lap in sixth before climbing to fourth - behind Simon, Pol Espargaro and Sandro Cortese - with ten of the 23 laps to go.
Simon had shaken off Espargaro and Cortese and was comfortably on course for his fifth win of the season when he made the unlikely mistake under braking, which left the Spaniard to rejoin in 13th place.
It also meant that Smith, Cortese and Espargaro were battling for victory, and the last lap began with Espargaro's Derbi in front by just 0.093sec from Smith and Cortese.
The trio fanned-out into turn one, with Cortese using the opportunity to snatch second from Smith, while Espargaro put his head down and pulled several bikelengths clear.
The Spaniard held that advantage to the line for a popular second win of the season, having been brought down at the final turn last time out at Misano, while Smith finished just 0.581sec from victory in third.
Twelfth place for Simon, who famously backed off one lap early while leading in Catalunya, means that he will start the Australian Grand Prix with a reduced 50.5 point lead over Smith, with a potential 75 points up for grabs.
Had he won the race, with Smith fourth, then Simon would have needed to score just half a point in Australia.
Race results - Estoril:
1. Espargaro (Derbi)
2. Cortese (Derbi) +0.395sec
3. Smith (Aprilia) +0.581sec
4. Bradl (Aprilia) +11.048sec
5. Olive (Derbi) +16.830sec
6. Gadea (Aprilia) +17.170sec
7. Rabat (Aprilia) +17.300sec
8. Aegerter (Derbi) +17.576sec
9. Zarco (Aprilia) +17.666sec
10. Krummenacher (Aprilia) +21.378sec
16. Redding (Aprilia) +54.332sec