Second seed Tommy Haas of Germany moved into the quarter-finals with a 6-4, 6-1 win over Denis Istomin of Uzbekistan.
Haas never faced a break point against serve in the 67-minute match against the world No .42 Istomin.
Taiwan’s Lu Yen-hsun crashed out after a 6-4, 3-6, 6-3 loss to Kevin Anderson of South Africa.
In other matches, qualifier Daniel Munoz-De La Nava of Spain upset eighth-seeded Xavier Malisse, a former two-time Delray champion, 7-6 (7/3), 3-6, 6-3; Ricardas Berankis of Lithuania defeated wild-card Jack Sock of the US 3-6, 6-4, 6-1; Eduoard Roger-Vasselin of France beat Ivo Karlovic of Croatia 6-4, 7-5; and Ivan Dodig of Croatia beat Evgeny Donskoy of Russia 6-3, 7-5.
Additional reoporting by Staff writer