World number 148 Evans was playing Harris for the first time
Briton Dan Evans surged into the Delray Beach Open quarter-finals in Florida with an emphatic 6-0 6-2 win against South African wildcard Lloyd Harris.
The 28-year-old British number three, a qualifier in this event, won the first nine games and secured a comfortable victory in an hour and eight minutes.
At the Rio Open, British number two Cameron Norrie lost a marathon second-round match to Jaume Munar of Spain.
World number 66 Munar won 7-6 (8-6) 5-7 7-6 (7-4) in three hours, 19 minutes.
Evans, who beat defending champion Frances Tiafoe in the previous round, faces Italian Andreas Seppi next.
Sixth seed Seppi beat Australian Jordan Thompson 6-3 4-6 6-1.
