Fifth seed Sara Errani suffered a shock Wimbledon first-round exit at the hands of Puerto Rican teenager Monica Puig.
The world number 65, playing her first senior match on grass, claimed a 6-3 6-2 victory over the Italian on Court 18.
Third seed Maria Sharapova is successfully through after overcoming a tight first set to beat world number 37 Kristina Mladenovic 7-6 (7-5) 6-3.
Second seed Victoria Azarenka survived an injury scare to secure a 6-1 6-2 win over Portugal's Maria Joao Koehler.
The reigning Australian Open champion recovered after being left in agony following a nasty fall in the second set which required lengthy treatment.
She will meet Italy's Flavia Pennetta in the next round following her win over Elena Baltacha.
Azarenka told BBC Two: "It's such a shock to me. I slipped and it felt like my whole body collapsed. I don't know what happened out there. I just tried to stay in the moment and give the best I could. It was definitely very emotional.
"I was in such pain at the beginning, it wouldn't stop. I almost slipped one time before that. It shouldn't be like that on grass, we are not on clay anymore. I will do the best I can just to be ready for the next match and we will see what happens."
Puig, 19, hit 38 winners on her way to victory over Italian Errani, who reached the quarter-finals in SW19 in 2012.
She broke her opponent four times and admitted she was 'thrilled' with the result.
"It was a very relaxed game for me. At the beginning I just blinked and I was up 6-3 5-1. I was able to close it out and I am very happy with this win.
"Everyone is super happy. My dad called me and he was ecstatic, my mum is here and she is very proud and my coach as well. I haven't stopped receiving messages so everybody is thrilled."
Number 12 seed Ana Ivanovic is safely through to the second round after a 7-6 (7-1) 6-0 win over world number 158 Virginie Razzano.
But the news was not so good for 26th seed Varvara Lepchenko as she was beaten 6-2 4-6 6-4 by Eva Birnerova who is ranked 152 in the world.