Toseland leads the championship by three points from Lacona

The Briton was three points behind Regis Lacona at the start of the day but a fourth and a second were enough to topple his Ducati Fila team-mate.

Australia's Chris Vermeulen joined the title race by winning both races at the Laguna Seca track.

"I'm a bit frustrated but all credit to Chris," said Toseland. "He never made a mistake out there."

Vermeulen, on a Ten Kate Honda, became only the third rider in 10 years to gain two wins in a day at this course and is now just 14 points adrift of Toseland.

"I'm a bit tired now as James pushed me hard all through the race," said Vermeulen.

"All credit to my team, it's the first time we've been here and they gave me a perfect bike to ride. "It's my first time at Laguna and only my second time in America and I love it here. The people are very friendly and the weather is great."

Round Seven race one:

1 Chris Vermeulen (Aus) Honda 41mins 03.371secs
2 Pierfrancesco Chili (Ita) Ducati 41:07.498
3 Steve Martin (Aus) Ducati 41:09.078
4 James Toseland (Gbr) Ducati 41:11.718
5 Regis Laconi (Fra) Ducati 41:11.761
6 Noriyuki Haga (Jpn) Ducati 41:21.931
7 Garry McCoy (Aus) Ducati 41:24.661
8 Mauro Sanchini (Ita) Kawasaki 41:35.166
9 Leon Haslam (Gbr) Ducati 41:37.537
10 Troy Corser (Aus) Petronas FP1 41:41.546
11 Marco Borciani (Ita) Ducati 41:46.925
12 Lucio Pedercini (Ita) Ducati 42:01.319
13 Piergiorgio Bontempi (Ita) Suzuki 42:21.623
14 Horst Saiger (Aut) Yamaha 42:25.903.

Retired: Chris Walker (Gbr) Petronas FP1 26 laps

Race two:

1 Chris Vermeulen (Aus) Honda 40min 56.568secs
2 James Toseland (Gbr) Ducati 40:57.033
3 Regis Laconi (Fra) Ducati 41:10.088
4 Noriyuki Haga (Jpn) Ducati 41:10.310
5 Pierfrancesco Chili (Ita) Ducati 41:18.338
6 Steve Martin (Aus) Ducati 41:24.532
7 Garry McCoy Garry (Aus) Ducati 41:40.199
8 Marco Borciani (Ita) Ducati 41:44.836
9 Mauro Sanchini (Ita) Kawasaki 41:45.895
10 Ivan Clementi (Ita) Kawasaki 41:50.589
11 Lucio Pedercini (Ita) Ducati 42:06.186
12 Bontempi Piergiorgio (Ita) Suzuki 42:21.012
13 Warwick Nowland (Aus) Suzuki (27 laps) 41:00.840
14 Horst Saiger (Aut) Yamaha (27 laps) 41:04.542