Jil Teichmann defeated Cristina Bucsa 6–3, 6–4 in the first round of the US Open on hard court on 31 August 2021, confirming her status as the pre-match favourite. Teichmann, who entered with odds of 1.21, controlled the match throughout against the 5.0 underdog Bucsa, securing a straightforward two-set victory. The Swiss player's composed performance on the hard courts of Flushing Meadows set up a second-round encounter and demonstrated early-round solidity in the year's final Grand Slam.