Japan's Naomi Osaka endured a challenge from Jessica Pegula of the United States in the first round of the China Open on Sunday to keep her Asian swing winning streak alive.

The world No. 4 and fourth-seeded Osaka survived a second-set tiebreak to claim a 6-3, 7-6(5) win over the No. 76 American at Beijing's National Tennis Center.

She will face either German qualifier Andrea Petkovic or Switzerland's Jil Teichmann in the second round.

Osaka smashed 26 winners to Pegula's 10 in their first career matchup, but the 21-year-old's first-serve percentage dropped from 93 percent in the first set to 65 in the second as she let her nerves work in Pegula's favor.

As her frustration mounted while trading sets, Osaka had a chance to close out the match when Pegula lost serve in the 11th game on a shot that went just long, but the American broke back to force a tiebreak.

Pegula fought back from 4-1 down to take a 5-4 lead, but with her father and current coach looking on, Osaka rattled off three straight points to seal a crucial win in the race to clinch a spot at the WTA Finals in Shenzhen starting late next month.

Last Sunday, Osaka won her first tournament in Japan in front of her hometown crowd and became the first Japanese player to win the Pan Pacific Open since Kimiko Date in 1995.

The former world No. 1 picked up her fourth WTA title and first since achieving her second straight Grand Slam win at the Australian Open in January.

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