Alex de Angelis claimed his first Moto2 victory of 2012 while champion-elect Marc Marquez fell late on and missed out on sealing the title in a crazy, rain-shortened Malaysian Grand Prix.
The Spaniard's exit means the title remains undecided, although with main rival Pol Espargaro finishing down in 11th Marquez remains a heavy favorite.
The downpour that had earlier delayed the start of the race had an even more marked effect once it started. Conditions ran from treacherously wet to dry and then back in little more than 17 laps, with the havoc of the weather reflected in a massively jumbled track order.
Nowhere was that more apparent than in the form of Malaysian wildcard Hafizh Syahrin who, from 27th on the grid, set a string of fastest laps and had soon moved into a shock lead. He began pulling away too, but a moment at Turn 1 marked the end of his spell at the front, allowing a trio of chasing riders – de Angelis among them – to close.
Syahrin held on to clinch fourth, but was not a feature of the three-way lead battle that raged over the final laps. De Angelis held the advantage but with three laps of the official distance to run first Gino Rea and then Anthony West moved ahead. The trio had already been swapping places at the front throughout the opening 15 laps.
As conditions steadily worsened, the race was halted, with Forward rider de Angelis earning the victory as the lap was counted back. West claimed second for QMMF, fractions ahead of Gresini's Rea, as both secured their first ever Moto2 podiums.
While the trio dueled, several other riders had trouble simply staying on the circuit. Marquez was among them, falling while trying to resist Andrea Iannone four laps from what was the eventual finish.
At the time Espargaro was 13th, meaning that even as Marquez despaired by the side of the circuit he was heading for the title.
Espargaro, helped by several other riders exiting, made his way up to 11th by the finish. The extra points gained keep the title race alive until at least Australia next weekend, although Marquez needs just two more to secure the crown.
Iannone ended the race sixth, behind Julian Simon, but ahead of Mika Kallio, Bradley Smith and Dominique Aegereter. Esteve Rabat claimed 10th ahead of Pons teammate Espargaro.