Marcos Giron was the highest seed in action on Wednesday at the San Diego Open, and he had little trouble dispatching Tomas Martin Etcheverry 6-4 6-3.
Giron, the third seed, was a force a from the baseline, collecting 18 winners in the first set, while Etcheverry could only muster six. While he was not as dominant in the second frame, Etcheverry helped him out with 14 unforced errors and five winners.
Giron will meet James Duckworth next after the Australian defeated America's Mitchell Krueger 6-3 7-6 (7-4).
Duckworth has now won six of his past eight matches, and he showed off his impressive serve against Krueger, winning the ace count 11-to-one.
Meanwhile, Mackenzie McDonald has earned a shot against his American compatriot and second seed Jenson Brooksby after hammering Switzerland's Henri Laaksonen 6-0 6-2.
McDonald was strong in all areas, but particularly in limiting his errors, finishing the match with no double faults and six unforced errors with 19 winners.
Rising Chilean talent Alejandro Tabilo used his powerful serve to overwhelm the similarly hard-serving Steve Johnson, winning 7-5 6-2.
Tabilo served 11 aces with no double faults, and won 80 per cent (41-of-51) of his total points on serve, while Johnson had three double faults with his seven aces and could only manage a 60 per cent (34-of-57) success rate on serve.
In an all-Australian matchup, Christopher O'Connell advanced past Jason Kubler after the latter was forced to retire due to injury with the match tied at 4-6 6-3 heading into the last set.