Navarro, seeded No. 2 overall, took down Hunter Horton 6-1, 6-4 to advance into the Round of 16 on Sunday. Ambarzumjan followed suit with a three-set win over Ignacio Bidegain. He dropped the first set 6-2 before rallying back to take the second set 7-5. His 6-3 third-set win gave Ambarzumjan the match to face George Barfoot Sunday at 11:30 a.m., while Navarro will take on Ryan Gaskin simultaneously.
Jordan Monosky fell in a three-set match to Tomas Hons in the first consolation round, taking the first set before falling in a tight second set and coming up short in a third-set tiebreaker.
In the B draw, ninth-seeded Nikhil Mannepalli defeated Oscar Marmestedt 6-3, 6-4 to advance to the Round of 16. He will face Yago Fernandez at noon.
Ambarzumjan and Navarro fell 8-5 in doubles action to the top-seeded duo. Mannepalli and Monosky fell by the same score in the B draw.