Canada's Gabrielle Daleman fell out of podium position to finish sixth at Skate America on Sunday.
The 19-year-old Toronto native was sitting in third after a stellar short program on Saturday but couldn't continue the momentum through to her free program. Daleman finished the day with a total score of 189.14.
"Technically it didn't go my way today," said Daleman. "That's the way this sport goes and that's the name of the game. I know what I need to work on and it is just a lot of repetition."
Japan's Satoko Miyahara finally recaptured her top form following a lingering hip injury, winning to cement herself as an Olympic favourite.
A three-time national champion, Miyahara skipped Four Continents and worlds this year because of her hip and finished fifth at the Grand Prix event in Japan. She said she's feeling better daily, and it showed in her programs this weekend.
Sakamoto had a score of 210.59, scoring especially well on her jumps, including a double axel-triple toe loop-double toe loop combination in the free skate.
Bradie Tennell emerged as a potential U.S. champion at her Grand Prix debut. The 19-year-old finished third at 204.10 with a season-best 137.09 in the free skate. Tennell shot her hands in the air when she finished her program, then smiled and covered her face.
"It was kind of just exactly what I'd been practicing," Tennell said. "I was just really happy I was able to put it out there and feel like I did my job."
Reigning Skate America champ Ashley Wagner halted her free skate and withdrew because of an infection on her right ankle. The 26-year-old American didn't appear to be injured, but stopped during a spin section. She said after she was in "nauseating" pain.
"It's not a quick-fix kind of a situation," Wagner said while choking up. "My main goal is to be national champion and to go to the Olympics, and that's something that I absolutely can do with the right amount of training."
U.S. skater Karen Chen finished eighth after a season-best score in the free skate. She had to ice her right knee Saturday after a fall in the short program and said she powered through a few big bruises to skate Sunday.
Russia's Polina Tsurksaya and Serafima Sakhanovich were fourth and fifth, respectively.
Gilles, Poirier finish 4th
The Shib Sibs say they're right on track for the Pyeongchang Olympics. First, a stop in Japan for a teaser showdown with the world's best.
American ice dancers Maia and Alex Shibutani skated into next month's Grand Prix Final with ease Sunday, winning Skate America for their second victory in the series with a program that could earn them gold in South Korea.
The two-time U.S. champions were a hit with fans and judges all weekend, twizzling and spinning their way to wins in the short and free dance programs. The siblings won the free skate Sunday with 115.07 points and finished at 194.25 overall. They also won the Grand Prix event in Russia this year.
"This was the week that we wanted to have at this particular point in the season," 26-year-old Alex Shibutani said.
The Shibutanis took bronze at last season's Final, and they'll try to do better against a strong field in Japan. Their top competition includes Vancouver winners and Sochi silver medalists Tessa Virtue and Scott Moir from Canada, and France's Gabriella Papadakis and Guillaume Cizeron — each of those duos also won two Grand Prix stops.
Two other American couples, Madison Chock and Evan Bates, and Madison Hubbell and Zachary Donahue, have qualified.
The Shibutanis are still looking for ways to sharpen their routine ahead of Pyeongchang.
"We know that this program still has room to grow," 23-year-old Maia Shibutani said.
Italy's Anna Cappellini and Luca Lanotte also qualified for the Final with a score of 181.63. The duo was upset with the judges' scores on the short program Saturday and then struggled in the free dance, with Cappellini's skate blade getting caught on Lanotte's pants during a lift. Lanotte said he let the short-program scores throw him off during the free dance.
Russia's Victoria Sinitsina and Nikita Katsalapov were third at 176.53. Canada's Piper Gilles and Paul Poirier were fourth at 166.54, and Kaitlin Hawayek and Jean-Luc Baker of the U.S. next at 163.53. The other American pair, Rachel and Michael Parsons, was ninth out of nine teams.
Canadian pair reaches Grand Prix Final
On Saturday, Meagan Duhamel and Eric Radford secured a spot in next month's Grand Prix Final by taking bronze in the pairs competition.
The Canadian duo led after Friday's short program but slipped to third place with their free skate and finished with a total score of 215.68, well off their personal best of 231.99.
Later Saturday, American skater Nathan Chen locked up a spot in his second straight Grand Prix Final, winning the men's competition despite a disappointing free skate.
Countryman Adam Rippon finished second and also qualified despite falling and dislocating his right shoulder on his first jump.
Liam Firus, from North Vancouver, B.C., was the top Canadian skater, finishing in eighth place. Kevin Reynolds of Coquitlam, B.C., finished ninth and Roman Sadovsky of Vaughan, Ont., was 10th.