London: Argentine ninth seed Juan Martin del Potro booked his passage into the fourth round at Wimbledon with a commanding straight-sets win over Japan's Kei Nishikori.
Del Potro fought off a second-set challenge from the 19th seed to win 6-3, 7-6 (3), 6-1 and set up a match with either seventh seed David Ferrer or former champion Andy Roddick.
Elsewhere in the men's draw, tenth-seeded Mardy Fish beat David Goffin of Belgium 6-3, 7-6 (6), 7-6 (6) on Saturday to reach the fourth round at Wimbledon, the American's first tournament since a medical procedure on his heart.
Del Potro fought off a second-set challenge from Japan's Kei Nishikori to win 6-3, 7-6 (3), 6-1.
Fish hit 17 aces and accumulated a total of 56 winners, 21 more than Goffin.
Fish also saved the only break point he faced, while breaking Goffin once — which was enough.
Hours after losing a match at Key Biscayne, Fla, in late March, Fish went to be checked by doctors after his heart started racing. He pulled out of the US Davis Cup team's quarterfinal against France the following week.
In May, doctors induced extreme palpitations to try to pinpoint the problem.
Fish reached the quarterfinals at Wimbledon last year, his best showing at the grass-court tournament.