Australian Alex de Minaur has bowed out of the Winston-Salem Open at the first hurdle, losing in straight sets to Daniil Medvedev.
The Russian broke the teenage world No.43's serve four times on the way to a routine 6-3 6-3 second-round win at the ATP 250 event in North Carolina on Tuesday.
The 19-year-old de Minaur was on the back foot throughout the one hour 32 minute encounter, saving 11 of 15 break points.
Medvedev was in cruise control at the other end, winning 77 per cent of his first serve points and blasting seven aces to de Minaur's two.
The 22-year-old world no.57 Russian snatched a critical second-set break to make it 5-3 before serving out the match.
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In his final lead-up tournament before next week's US Open, 15th-seeded de Minaur - who reached his second ATP final at the Citi Open in early August - had an opening-round bye.
Other players to progress to the round of 16 were American eight seed Steve Johnson, 16th-seeded German Peter Gojowczyk, Matteo Berrettini and Jaume Munar.
