Gibbs won 6-4, 6-3 over Alison Riske in the first round of Osaka on Monday.
Gibbs, who qualified for the main draw here, surprised her countrywoman who is more than 100 spots higher than her in the rankings as she won comfortably in straight sets. The win marks the first for the 26-year-old American since her return from cancer earlier this summer. She'll get a meeting with No. 4 seed Angelique Kerber in Round 2, who she has never faced.