Defending champion Serena Williams got her Wimbledon campaign off to a winning start when she beat unheralded Swiss player Amra Sadikovic in straight sets on Tuesday.
In a match lasting an hour and 15 minutes, the top seed triumphed 6-2, 6-4.
Although her opponent carved out two break points in the opening game, it was the world number one who broke first, in the second game, and opened up a 5-2 lead before Sadikovic lost her serve once more in the eighth game to hand the American the opening set.
It was Sadikovic who drew first blood in the second set, breaking serve in the third game, but that was as good as it got for the world number 148, who lost her serve at the next time of asking.
The match went with serve until Williams broke again in the 10th game to book her spot in the second round.
Joining her in the second round is compatriot Christina McHale, who beat Daniela Hantuchova 7-5, 6-4, and 18th seed Dominika Cibulkova, who beat Mirjana Lucic-Baroni 7-5, 6-3.
The Chinese contingent had a mixed day at SW19 on Tuesday, with Ying-Ying Dong advancing but Qiang Wang was knocked out at the first time of asking.
Duan claimed a 6-3, 3-6, 7-5 victory over Kristyna Pliskova, while Wang suffered a 2-6, 6-3, 6-4 defeat to Daria Gavrilova.