Andrea Iannone has won the 125cc Japanese Grand Prix at Motegi, after being rewarded for a slick tyre choice.

The race began on a damp, but rapidly drying track, prompting a range of tyre options throughout the field.

Predictably, it was those on the 'wetter' options that enjoyed an early grip advantage, but the blazing sunshine turned conditions ever more in favour of the slick/cut slick riders.

13th on the grid Danny Webb dominated the first half of the event on his wet weather Dunlops, the young Briton building a mighty nine-second lead over Simone Corsi and Nicolas Terol by lap 8 of 20.

But it was pre-season favourite Julian Simon, using cut slicks, who was increasingly making an impression - claiming second position just before the halfway stage and gaining visibly on Webb with every lap.

The Aspar Aprilia rider took the lead from Webb on lap 13, but pole sitter Iannone had made an even bigger gamble - opting for full slicks - and was within four seconds of the lead.

Iannone passed Simon along the start/finish straight with three to go and claimed his second victory in a row - but first with full points, following the four-lap Qatar sprint - by 1.346sec from the Spaniard.

Pol Espargaro completed the podium, five seconds behind Iannone.

Simon's team-mate Bradley Smith smashed his screen during a near highside in the closing stages - cutting his face in the process - but rode on to claim tenth position before heading for the medical centre.

Webb's valiant effort was ultimately undone by the weather and he crossed the finish line in eleventh for Degraaf Aprilia.

Race results - Motegi:

1. Iannone (Aprilia)
2. Simon (Aprilia) +1.346sec
3. Espargaro (Derbi) +5.039sec
4. Bradl (Aprilia) +6.904sec
5. Marquez (KTM) +13.061sec
6. Cortese (Derbi) +14.841sec
7. Olive (Derbi) +16.420sec
8. Folger (Aprilia) +16.483sec
9. Aegerter (Derbi) +27.500sec
10. Smith (Aprilia) +30.359sec

11. Webb (Aprilia) +37.547sec

Redding (Aprilia) DNF
Hoyle (Haojue) DNS