Defending champion Cristian Garin was victim of the biggest shock of Tuesday's play at the Rio Open.
Fifth seed Garin – winner of the most recent edition in 2020 – exited a second consecutive tournament at the first-round stage after he was humbled by Federico Coria.
Coria had defeated the fifth seed, Dusan Lajovic, at last week's Argentina Open, too, but was particularly impressive on Tuesday.
A stunning 6-2 6-0 win was sealed in an hour and 16 minutes.
Coria fended off two break points midway through the first set and then won the remaining nine games in succession in a dominant victory.
Garin was the only seed to lose in Brazil, however, as Lorenzo Sonego was on the right side of a 6-2 6-0 scoreline against 2019 winner Laslo Djere.
Fabio Fognini also advanced in straight sets, while Spanish pair Albert Ramos-Vinolas and Fernando Verdasco similarly eased through.
At the Delray Beach Open, 2021 runner-up Sebastian Korda defeated Thanasi Kokkinakis in his first match since winning the Australian Open doubles title with Nick Kyrgios.
Former champion Sam Querrey came up short against Denis Istomin.