USA's Serena Williams returns to Japan’s Naomi Osaka in the first round of the Miami Masters in Florida on Wednesday. pic/AFP

Serena Williams crashed out of the Miami Open in the first round here on Wednesday, slumping to a straight sets defeat against Japan's Naomi Osaka in the latest setback to her comeback. Osaka, who won her first major title in Indian Wells last weekend, was superior throughout and fully deserved her 6-3, 6-2 win in just one hour and 17 minutes. It was Williams' fourth match and second tournament appearance since returning from 13 months of maternity leave — yet the American's movement and inability to stay in the rallies suggested her comeback could be more arduous.