Tennys Sandgren fired 15 aces and began his title defense at the ASB Classic with a 6-4, 6-3 win against New Zealand's Michael Venus on Monday in Auckland.
Up next for the 28-year-old Sandgren is an all-American clash with No. 4 seed and two-time Auckland champion John Isner.
No. 6 seed Hubert Hurcacz of Poland saved all four break points he faced in a 7-5, 6-3 win against Italy's Lorenzo Sonego. Brazilian Thiago Monteiro rallied from 2-4 down in the first set for a 7-6 (3), 6-2 win over last year's runner-up, Cameron Norrie of Great Britain.
No. 5 seed Benoit Paire of France outlasted 18-year-old Italian Jannik Sinner 6-4, 2-6, 6-4, and Frenchman Ugo Humbert beat Norway's Casper Ruud 7-6 (3), 2-6, 6-3.
France's Jeremy Chardy beat countryman Gilles Simon 6-3, 7-5 to reach the second round in Adelaide, Australia.
It was Chardy's third straight win in their head-to-head series following an 0-4 start. He will face fourth-seeded Spaniard Pablo Carreno Busta in the second round.
Sam Querrey struck 28 aces and never faced a break point while winning a 6-7 (4), 6-2, 7-6 (5) battle with French qualifier Gregoire Barrere. Britain's Dan Evans defeated Argentina's Juan Ignacio Londero 6-2, 6-4.
Lloyd Harris of South Africa knocked out No. 6 seed Cristian Garin of Chile 7-6 (5), 3-6, 6-4. Harris will face Serbian Laslo Djere, a 7-6 (3), 3-6, 6-4 winner over Australia's Alexei Popyrin.
--Field Level Media