Dominic Thiem was tested before reaching the Argentina Open semi-finals, while John Isner cruised through in New York.
A two-time champion in Buenos Aires, Thiem overcame Pablo Cuevas 4-6 6-4 6-3 in their quarter-final on Friday.
The top seed improved to 11-0 at the ATP 250 event, where Diego Schwartzman awaits in the last four.
The fourth-seeded Schwartzman was too good for Albert Ramos-Vinolas in a 6-1 7-5 victory.
#CuartosDeFinal | #ArgOpen2019
— Argentina Open (@ArgentinaOpen) February 16, 2019
¡@dieschwartzman es el último semifinalista!
Victoria sobre @albertramos88 por 6-1 y 7-5
Enfrentará en semifinales a su amigo @ThiemDomi pic.twitter.com/aH3BdEaLDW
The other semi-final will see Italian third seed Marco Cecchinato meet Guido Pella.
Cecchinato got past Roberto Carballes Baena 7-6 (7-3) 6-4, while Pella saved four match points in a 6-7 (3-7) 7-6 (11-9) 6-1 win over Jaume Munar.
At the New York Open, Isner served 16 aces in a 6-4 6-1 win over Australian seventh seed Jordan Thompson.
And the winner of the first set is...@JohnIsner at 6-4 vs. @jordanthommmo2 . #NYOpen19 #BackInBlack pic.twitter.com/9o741uBDMa
— New York Open (@NewYorkOpen) February 16, 2019
He will face fellow big-serving American Reilly Opelka in the semi-finals after the 21-year-old beat Guillermo Garcia-Lopez 6-3 6-4.
Last year's runner-up Sam Querrey overcame Jason Jung 6-3 3-6 6-3 and next meets Canadian qualifier Brayden Schnur, who edged Paolo Lorenzi 6-7 (7-9) 7-6 (7-5) 7-5.