RIO DE JANEIRO: World number two Carlos Alcaraz overcame 556th-ranked Mateus Alves of Brazil in a rain-delayed opening match Wednesday to advance to the second round of the ATP Rio Open.Reigning Rio champion Alcaraz, who returned last week after four months out because of injury, started his title defense at the clay-court tournament Tuesday.However, he and Alves had their match interrupted by a torrential downpour with the 19-year-old Spaniard leading 6-4, 5-3.Home-crowd favorite Alves, 22, who had pushed Alcaraz harder than expected Tuesday, looked determined to mount a comeback when play resumed on stadium court, winning the first game.