Both top seed Taylor Fritz and Casper Ruud, second-seeded second, won their opening matches at the Japan Open on Tuesday.
Fritz beat 18th-ranked Cameron Norrie 6-4, 6-3 and Ruud defeated wild card entry Yosuke Watanuki 7-6 (8), 6-3.
Fritz, ranked 10th in the world, had 13 aces and broke Norrie three times to improve to 7-6 against the British player.
The 25-year-old American will next play Japanese wild card Shintaro Mochizuki, who beat Tomas Martin Etcheverry 6-4, 7-6 (5).
Ruud will next face American player Marcus Giron.
Other winners included Alex de Minaur, Alexei Popyrin, Ben Shelton, Cristian Garin and Diego Schwatzman.
On Monday, Jordan Thompson upset ninth-ranked Alexander Zverev 6-3, 6-4 for his second win over a top-10 opponent this season.
Haddad-Maia exits
Top-seeded Beatriz Haddad-Maia and second-seeded Magda Linette were both eliminated in the first round of the Jiangxi Open. Nao Hibino upset Haddad-Maia 7-6 (2), 6-3, while Valeria Savinykh beat Linette 7-5, 3-6, 7-6 (3).
Sixth-seeded Anna Blinkova fell to Chinese qualifier You Xiaodi 6-1, 6-1, while Leylah Fernandez defeated wild card Guo Hanyu 6-1, 6-3.
AP/PTI
