Tennis: Del Potro grinds down Raonic in Miami, Isner also advances

(Reuters) – Juan Martin del Potro remained on course for a rare Sunshine Double when he outlasted Milos Raonic 5-7 7-6(1) 7-6(3) in a marathon quarter-final at the Miami Open on Wednesday. Del Potro, who claimed the Indian Wells title earlier this month, fed off the energy of a raucous crowd that was