NEW YORK (AP) -- Serena Williams started her bid for a record-breaking 23rd major title by showing zero signs of trouble from a right shoulder she's said was sore, hitting 12 aces in a 6-3, 6-3 victory over Ekaterina Makarova. Also under the lights later: Andy Murray vs. Lukas Rosol.
Earlier, Williams' sister Venus got through a tougher-than-expected 6-2, 5-7, 6-4 win against Kateryna Kozlova.
"It was great to be challenged and to be pushed," said the 36-year-old Venus, a two-time U.S. Open champion, "because I had to get in those situations that you know you're going to face in the tournament."
There were various upsets around the grounds during the afternoon, including 19-year-old American Jared Donaldson's 4-6, 7-5, 6-4, 6-0 elimination of 12th-seeded David Goffin, and a loss by No. 29 Sam Querrey, who stunned Novak Djokovic at Wimbledon. Three seeded women departed, including former No. 1 and 2008 French Open champion Ana Ivanovic.