MIAMI (AFP) - US second seed John Isner blasted 24 aces Friday (Feb 22) in defeating France's eighth-seeded Adrian Mannarino 7-6 (7/2), 6-4 and advancing to ATP Delray Beach Open semi-finals.
Ninth-ranked Isner, who has dropped only one set in seven career wins over the left-hander, needed only 93 minutes to book a spot in the last four against Britain's Daniel Evans.
Italian sixth seed Andreas Seppi fell to Evans, the 148th-ranked Englishman dispatching 52nd-ranked Seppi 6-4, 6-4.
World number four Juan Martin Del Potro of Argentina plays American Mackenzie McDonald in a later quarter-final, the winner to meet either US fourth seed Steve Johnson or Moldova's Radu Albot in Saturday's other semi-final.
Del Potro, the 2011 Delray Beach champion, is playing his first tournament since breaking his right kneecap at the Shanghai Masters in October.
Top seed Del Potro seeks his 23rd career ATP singles title and his first since last year at Indian Wells.