Colombian qualifier Alejandro Falla upset French eighth seed Adrian Mannarino 6-3, 6-2 on Thursday to reach the quarter-finals of the ATP Delray Beach International Championships.
The 119th-ranked South American opened with a break and closed out the match in 77 minutes with another break to win the battle of the left-handers and oust 61st-ranked Mannarino from the $442,500 event.
Falla will try to qualify Friday for only his second ATP semi-final, his first since 2007 in Lyon, when he faces US second seed Mardy Fish, who needed only 57 minutes to beat Brazil's Ricardo Mello 6-2, 6-1.
"I felt great," Fish said. "I couldn't be happier, obviously, with the way it's gone this week."
Fish is the top-ranked player on the Florida courts this week after top seed Andy Roddick pulled out due to illness.
In the night match, Juan Martin del Potro of Argentina crushed Teymuraz Gabashvili of Russia 6-1, 6-1.
Del Potro never offered Gabashvili a break point chance in the 69-minute contest. Gabashvili held serve just twice -- the second game of the second set and once in the first set.
"I had a good night and I feel very well," Del Potro said. "I played nice tennis again. I think it's a positive that the match was short and I'll have more time to recover for tomorrow's match."
Del Potro will play fifth-seeded South African Kevin Anderson in the quarter-finals. Anderson easily defeated Florent Serra of France 6-1 6-4 in the other late match.