It was smooth sailing for the seeded competitors in action on Wednesday at the Atlanta Open, with Tommy Paul, Frances Tiafoe and Brandon Nakashima all advancing in straight sets.

Fifth seed Paul started the day off with a straightforward 6-3 6-3 win against South Korea's Kwon Soon-woo thanks to a clear advantage with his serving. He won 73 per cent (36-of-49) of his points on serve, while Kwon could only muster 53 per cent (34-of-64).

Paul will meet Belarus' Ilya Ivashka in the quarter-finals after he successfully navigated the challenge of America's Steve Johnson 4-6 6-2 6-4 after Johnson was a late injury replacement for top overall seed Reilly Opelka.

Ivashka is now 6-3 in his nine matches since the French Open, with his only losses against top-five talents Stefano Tsitsipas and twice against Daniil Medvedev.

Fourth seed Tiafoe was impressive against Japan's Taro Daniel, creating eight total break point opportunities, and capitalising on three. 

Tiafoe will play Nakashima in the quarter-finals, with the American surviving a tough first set tiebreaker to eventually defeat Australia's John Millman 7-6 (10-8) 6-4.

In a closely contested match, Nakashima avoided getting into many sticky situations, saving the only break point he faced.