Brazil's Thiago Monteiro knocked out fifth seed Horacio Zeballos before rain suspended play for the day at the Ecuador Open in Quito.
The 23-year-old won 6-4 7-6 (10/8) in the first round of the competition, after one hour and 39 minutes on court.
Spain's Roberto Carballes Baena beat Italian Federico Gaio 7-6 (7/5) 6-3 in the only other completed match of the day.
Play will resume on Wednesday with seventh seed Ivo Karlovic facing Ernesto Escobedo of the United States.
Sixth seed Viktor Troicki ended the hopes of former world number 10 Ernests Gulbis with victory in their first-round clash at the Sofia Open in Bulgaria.
Latvian Gulbis, now ranked 199, had come through qualifying by beating Florian Mayer but despite forcing a deciding set, he was defeated by Troicki as the Serbian progressed 6-3 6-7 (2/7) 6-3.
German Mayer had also made it into the first-round draw as a lucky loser, but went down 6-4 6-1 to Mirza Basic of Bosnia.
Slovak Martin Klizan beat Alexander Donski of Bulgaria 7-5 6-1 to set up a second-round contest against top seed Stan Wawrinka, the Swiss world number 15.
Denis Istomin defeated Adrian Andreev 6-3 6-4, and the Uzbek player will next face Troicki, while qualifier Jozef Kovalik progressed after beating Radu Albot 6-3 6-3.
Tuesday's late match saw number seven seed David Ferrer of Spain suffer a surprise defeat to Russian Karen Khachanov as the 21-year-old won through 6-7 (5-7) 6-3 6-4.
At the Open Sud de France in Montpellier, home player Gilles Simon saw off the challenge of German qualifier Yannick Maden 6-1 4-6 7-6 (7/3) to book his place in the second round against top seed David Goffin.
Jeremy Chardy is also through as he beat Stefanos Tsitsipas of Greece 4-6 7-5 7-5, but wildcard Julien Benneteau is out after a 6-3 7-6 (8/6) loss to Lithuanian Ricardas Berankis.
Spain's Carlos Taberner recorded a 7-6 (7/5) 7-6 (7/1) win over Slovakian Norbert Gombos.