Colin Edwards produced his best result of the 2010 season with fifth place in Yamaha's home event at Motegi on Sunday.
The Monster Yamaha Tech 3 rider held fifth for the opening two laps, then lost it to Gresini Honda rookie Marco Simoncelli on lap 3, before re-passing the Italian on lap 18 of 24.
The 36-year-old, who has re-signed with Tech 3 for 2011, then opening up a three second gap on Simoncelli to secure his best finish since the final round of 2009 in Valencia.
“In terms of the result I'm really happy because it is my first top six finish of the year and I think it was deserved after all the hard work the Monster Yamaha Tech 3 Team and me have been putting in to improve our results," said Edwards. "And it is always good to get a result in Japan with the race being so important for Yamaha and the Tech 3 Team.
"I rode good all weekend and was only four-tenths off pole, but what I'm a little disappointed about is that I'm 27 seconds behind the winner. That's a big chunk of time and I'm riding as hard as I can. I feel comfortable and I feel good on the bike now we improved the setting but I guess we just have to shoot for being top non-factory rider.
"It was hard in the first few laps because I didn't have a lot of feel in the left-side of the rear tyre. But once I got confident, Simoncelli passed me but I was happy just to sit behind him and study him, check where I was faster while making sure I wasn't going to leave the door open for Capirossi.
"I think my rear tyre had good grip for a little bit longer than Simoncelli's and I managed to pass him, put my head down for a couple of laps and managed to pull a gap."
Team manager Herve Poncharal was pleased to see his rider back on form.
“Colin had by far his best result of the season and this weekend he has been back to the outstanding form he showed all last season," said the Frenchman. "He's been working hard with his Monster Yamaha Tech 3 crew for several races now to improve and this weekend that effort paid off. He had a good battle with Simoncelli that Colin won comfortably and I think we saw he used his experience today."
Team-mate Ben Spies finished eighth after running off track on lap two.