Playing in his hometown of Buenos Aires, Francisco Cerundolo avenged his younger brother's defeat at the Argentina Open by defeating Yannick Hanfmann 6-2 4-6 7-5 on Tuesday.
Francisco's younger brother Juan Martin had been eliminated by Hanfmann in the qualifying stage, but the fifth seed got one back on the German after leading the break point opportunities 17 to six.
Fifth-seed Cerundolo was the highest seed in action Tuesday, while sixth seed Sebastian Baez fell 3-6 7-6 (7-5) 6-3 to Serbia's Dusan Lajovic.
In the only all-Argentine clash it was Facundo Diaz Acosta prevailing 7-6 (7-5) 7-5 against Federico Coria – who sits over 100 places higher in the rankings – while Roberto Carballes Baena collected a seeded scalp with a 7-5 6-4 win over Spanish compatriot Albert Ramos-Vinolas.
Meanwhile, Australian Open quarter-finalist Ben Shelton was eliminated from his own hometown tournament as the Florida resident was bounced out of the Delray Beach Open 6-4 6-4 by Marcos Giron.
Shelton beat J.J. Wolf to reach that grand slam quarter-final, but Wolf will be moving on after he emerged with a 7-5 6-3 win against Ilya Ivashka.
Wolf will play France's Adrian Mannarino following his 4-6 6-3 6-4 triumph over Germany's Daniel Altmaier, and Mackenzie McDonald will get a shot at redemption against fifth seed Yoshihito Nishioka after a comfortable 6-2 6-2 success against Taro Daniel.
McDonald and Nishioka have played twice this year – once at the Adelaide Invitational and once at the Australian Open – and Nishioka has won all five sets.
It was also a day 33-year-old Matija Pecotic will never forget, with the world number 784 winning his first ever ATP Tour match by defeating Jack Sock 4-6 6-2 6-2.