Top seed and world number eight Taylor Fritz made a winning start to his Dallas Open campaign on Thursday, eliminating Jack Sock 7-6 (7-5) 6-4.

In an all-American showdown, Fritz played a near-flawless match, converting 91 per cent of his accurate first serves into points while not allowing Sock a single break point opportunity.

Fritz will face seventh seed Marcos Giron in the quarter-final after the American defeated Germany's Oscar Otte 6-4 6-3, while the USA's John Isner also advanced past Germany's Daniel Altmaier 6-3 7-6 (7-1).

Earlier in the day, Serbian fourth seed Miomir Kecmanovic was upset by Ecuador's Emilio Gomez 2-6 7-6 (7-4) 6-4 to earn a crack at Isner in the quarter-finals.

Meanwhile, the top seed fell at the Cordoba Open as red-hot 21-year-old Juan Manuel Cerundolo shocked his Argentinian compatriot Diego Schwartzman 7-6 (8-6) 6-1.

It continues a remarkable run for Cerundolo – the defending champion in Cordoba – who has begun 2023 with 14 wins from his first 15 matches, while his older brother Francisco Cerundolo also advanced with a 6-3 3-6 7-5 win over Federico Delbonis.

If the two brothers both win their next two matches, they will meet in the final.