Capirossi celebrates after his imperious victory at Motegi

Polesitter Capirossi, who broke his own track record in qualifying, rarely looked in trouble in a fine win.

But all eyes were on Yamaha's resurgent Rossi, who closed the gap on overall leader Nicky Hayden to just 12 points with two races remaining this season.

American Hayden limped to fifth spot after struggling on his Repsol Honda.

Even then, the 25-year-old owed his 11-point haul to a late crash by Shinya Nakano on the final corner after the Japanese rider spun out of control attempting to pip Sete Gibernau to fourth spot.

The points I picked up today are very important for the championship...I'm pleased with the result Valentino Rossi

Hayden maintained his record of having scored points in every race this season, but with two races left, in Portugal and Spain, his title hopes have taken a serious knock.

"Another fifth obviously isn't great," he said.

"The start was a bit of a disaster. It was the worst part of the race. Lap one was pretty wild."

But Rossi was delighted to close the gap on his rival.

"The points I picked up today are very important for the championship," said the 27-year-old, who is chasing his sixth straight premier-class title.

"This isn't my favourite track but everyone did a good job of getting the bike ready and I'm pleased with the result."

Marco Melandri made it an all-Italian top three, with Capirossi admitting being pushed all the way by his compatriots made his victory all the sweeter.

He said: "It was an amazing race, especially after I got a good start.

"Marco stayed close and then Valentino was coming so I had to push hard till the end. It's the second time to win here and it's a great feeling."

Meanwhile, Dani Pedrosa's championship hopes receded after he struggled to seventh spot on his Honda, completing a frustrating weekend for the 20-year-old.

Briton James Ellison scraped into the points, finishing 15th after starting 19th on the grid.

Japanese MotoGP results:
1. Loris Capirossi (Ita) Ducati 43:13.585
2. Valentino Rossi (Ita) Yamaha 43:18.673
3. Marco Melandri (Ita) Honda 43:21.963
4. Sete Gibernau (Spa) Ducati 43:23.297
5. Nicky Hayden (US) Honda 43:25.529
6. Toni Elias (Spa) Honda 43:31.693
7. Dani Pedrosa (Spa) Honda 43:33.522
8. Colin Edwards (US) Yamaha 43:36.077
9. Kenny Roberts Jr. (US) KR211V 43:40.409
10. Makoto Tamada (Jap) Honda 43:44.555
11. Chris Vermeulen (Aus) Suzuki 43:52.848
12. John Hopkins (US) Suzuki 43:53.025
13. Kousuke Akiyoshi (Jap) Suzuki 44:59.180
14. Carlos Checa (Spa) Yamaha 44:03.156
15. James Ellison (GB) Yamaha 44:22.670

MotoGP Standings:
1. Nicky Hayden (US) Honda 236
2. Valentino Rossi (Ita) Yamaha 224
3. Marco Melandri (Ita) Honda 209
4. Loris Capirossi (Ita) Ducati 205
5. Dani Pedrosa (Spa) Honda 202
6. Casey Stoner (Aus) Honda 119
7. Kenny Roberts Jr. (US) KR211V 110
8. Colin Edwards (US) Yamaha 104
9. John Hopkins (US) Suzuki 101
10. Sete Gibernau (Spa) Ducati 95

250cc race result (Sun):
1 H Aoyama (Jpn) KTM 43mins 36.310secs
2 A De Angelis (SM) Aprilia 43:37.651
3 J Lorenzo (Sp) Aprilia 43:40.659

Championship Standings:
1 J Lorenzo (Sp) Aprilia 265pts
2 A Dovizioso (It) Honda 238
3 A De Angelis (SM) Aprilia 187

125cc race result (Sun):
1 Kallio (Fin) KTM 41mins 40.970secs
2 A Bautista (Sp) Aprilia 41:41.155
3 J Simon (Sp) KTM 41:48.739