New 125cc world champion Julian Simon has won his sixth race of the season with a narrow victory over team-mate Bradley Smith in the Malaysian Grand Prix at Sepang.
Simon, who clinched his first world title with a final lap victory over Smith last Sunday at Phillip Island, took the lead on lap two of 19 and had begun to break away from the pack by lap five.
But Smith went with him and the Aspar Aprilia team-mates had pulled a four-second advantage over Pol Espargaro by the midway point of the race - the Derbi rider narrowly leading a frantic seven-rider fight for third.
Smith, who broke a bone in his foot during a qualifying highside on Saturday, shadowed the Spaniard until finally outbraking Simon into the final hairpin at the end of lap 13.
The Englishman, chasing his third grand prix victory of the season, tried to shake-off Simon - but the #60 stubbornly remained in his wheel tracks and was rewarded when Smith made a mistake on corner-entry with three laps to go.
Smith regrouped and began the last lap just 0.432sec behind Simon, who soon found Smith breathing down his neck - then looked the wrong way, allowing Smith alongside.
But Simon held the inside line at the following turn and it all came down to an out-braking battle into the final hairpin - and Simon, who has been backing his 125 into turns for much of the season, unsurprisingly came out on top.
The good news for Smith was that he confirmed second in the world championship, with one round remaining, after rival Nicolas Terol only managed fifth on Sunday.
Helped by accidents and incidents around him, Espargaro gained vital breathing room in the closing stages to claim a safe third - from just eleventh on the grid.
Among those that made a premature exit from the group were Jonas Folger, pole sitter Marc Marquez, Efren Vasquez and Simone Corsi. Folger, Vasquez and Corsi all fell, while Marquez suffered an engine seizure on his KTM.
Race results - Sepang:
1. Simon (Aprilia)
2. Smith (Aprilia) +1.114sec
3. Espargaro (Derbi) +6.293sec
4. Gadea (Aprilia) +8.003sec
5. Terol (Aprilia) +8.485sec
6. Cortese (Derbi) +10.188sec
7. Rabat (Aprilia) +15.114sec
8. Iannone (Aprilia) +22.151sec
9. Olive (Derbi) +26.388sec
10. Zanetti (Aprilia) +27.113sec
Webb (Aprilia) DNF
Redding (Aprilia) DNF