Thiem stays perfect in Buenos Aires, Ferrer exits
Dominic Thiem maintained his perfect record at the Argentina Open to reach the quarter-finals, while David Ferrer was edged on Thursday.
Thiem, a two-time champion in Buenos Aires, was too good for German Maximilian Marterer 6-4 6-4 in the second round.
The top seed is now 10-0 at the ATP 250 event, which he won in 2016 and last year but skipped in 2017.
Thiem will face Pablo Cuevas in the last eight after the Uruguayan overcame fifth seed Joao Sousa 6-4 7-5.
Ferrer, 36, suffered just his second loss in eight meetings with Albert Ramos-Vinolas, going down to his fellow Spaniard 3-6 7-6 (11-9) 6-3 after squandering two match points.
Ramos-Vinolas will face Diego Schwartzman, who got past Aljaz Bedene 6-4 2-6 6-2.
At the New York Open, seeds Frances Tiafoe and John Millman made second-round exits.
Tiafoe was beaten by Jason Jung 6-3 7-5 and Millman went down to Guillermo Garcia-Lopez 7-6 (7-4) 1-6 6-4.
American sixth seed Sam Querrey progressed with a 6-3 6-4 win over Radu Albot, while Reilly Opelka led Denis Istomin 6-7 (8-10) 7-6 (8-6) 1-0 when the Uzbek retired.