KEY BISCAYNE, Fla. — Not even the hometown favorite and three-time defending champion, Serena Williams, or the men’s No. 2 player, Andy Murray, is immune to the spate of bad luck that has befallen players at this year’s Miami Open.
Williams, the top-ranked woman, was upset by No. 19 Svetlana Kuznetsova, 6-7 (3), 6-1, 6-2, in her fourth-round match Monday, immediately after No. 2 Agnieszka Radwanska lost to No. 20 Timea Bacsinszky in three sets, 2-6, 6-4, 6-2. Soon after Williams’s match, Murray, who is from England but owns a home in Miami and trains at Crandon Park, fell to No.