Serena Williams overcame a minor second-set blip to begin the defence of her Wimbledon crown with a 6-1 6-3 win over Mandy Minella of Luxembourg.
The world number 92 claimed her first service game but the American, 31, took control and easily won the first set.
Minella claimed a break in game two of the second set only for the five-time champion to win six straight games.
Seeds Agnieszka Radwanska, Li Na and Angelique Kerber all progressed with straight-sets wins.
Polish fourth seed Radwanska, beaten by Williams in last year's final, began her bid to go one better with a 6-1 6-1 win over Austrian qualifier Yvonne Meusberger.
Chinese sixth seed Li raced past her Dutch opponent Michaella Krajicek 6-1 6-1, while Kerber, the seventh seed, triumphed 6-3 6-4 over Bethanie Mattek-Sands.
German Kerber is a potential quarter-final opponent for Williams, who arrived at SW19 on the back of claiming a second French Open title earlier this month.
Williams told BBC Sport: "I played so much on clay this year it meant the grass transition was harder than I expected."
Top seed and 16-time Grand Slam champion Williams refused to use her recent row with Maria Sharapova as an excuse for what she labelled a "rusty" performance - despite it extending her winning streak to 32 matches.
She added: "No, it hasn't been a distraction. Like I said, I'm just here to focus on the tennis. I'm just here to play Wimbledon. It's the premier tournament in the world, of the year, so that's what's most important.
"It felt good to be playing tennis again. I love playing here. Being defending champion is always a special moment for 12 months knowing that you're going to play at one o'clock on Tuesday."
There were also victories for 14th seed Samantha Stosur, who defeated Anna Karolina Schmiedlova 6-1 6-3 and 11th seed Roberta Vinci overcame Chanelle Scheepers of South Africa 6-2 6-1.
Peng Shuai of China, the 24th seed, recorded a 6-3 6-2 triumph over Anabel Medina Garrigues, 30th seed Mona Barthel beat Monica Niculescu of Romania 6-3 4-6 7-5 and 42-year-old Kimiko Date-Krumm was a 6-0 6-2 winner over Carina Witthoeft.
Date-Krumm, the oldest woman in the main draw, revealed after her win over the 18-year-old German qualifier that she has a secret weapon in her bid to compete with younger opponents.
"I'm taking care of my body, because of course the most difficult thing is recovery. I need more training. But if I do too much I feel tired," said Date-Krumm, whose opponent was just four when the Japanese player made her Wimbledon debut in 1989.
"I like Chinese tea. Sometimes Japanese tea. I drink a lot. I have a tea pot I always carry. It's here with me now."
Sabine Lisicki, the 2011 semi-finalist, rushed through a late-evening win over 2010 French Open winner Francesca Schiavone, 6-1 6-2, but there were defeats for 13th seed Nadia Petrova and Austrian Tamira Paszek.
Russian Petrova was beaten by Karolina Pliskova of the Czech Republic, while 28th seed Paszek lost to Romanian Alexandra Cadantu, both in straight sets.