and trail 2-4.
Osaka broke serve after delivering more powerful baseline tennis to reach 3-4.
Serving with new balls, Osaka double faulted twice before striking a down the line backhand long to drop serve and trail 3-5.
Serving for the match, Teichman struck a crosscourt forehand volley winner to lead 15-0.
Both players then committed one groundstroke error each to reach 30-15.
The Swiss then struck a down the line forehand winner to set up match point at 40-15.
Teichman netted a down the line backhand to reach 40-30.
Osaka shouted "come on" and gave a fist pump but it was too late.
The 23 year old Osaka struck an inside out forehand return long to end the match.
Teichman in the third round night match, defending and moving well, converted 6 of 12 breakpoints while Osaka struck 41 unforced errors.
Osaka, the 2018 and 2020 US Open champion, is set to begin her title defense starting on Monday in New York City.