But the American has struggled for form since returning to competitive action losing to sister Venus in Indian Wells and Naomi Osaka in Indian Wells. Aside from Serena she has the most experience and is mentally tougher.
As she served for the match, she slipped into the net, righting herself sporting an embarrassed smile.
Serena Williams made her first Grand Slam appearance as a mother at Roland Garros on Tuesday.
Azarenka herself wasn't given a seeding at Wimbledon a year ago after returning to the game following the birth of her son.More news: Apple releases iOS 11.4 with AirPlay 2
"We talk a lot, obviously".
Azarenka did call for the rules to be changed to differentiate between injury absences and spells on the sidelines due to pregnancy.
"I don't really think so", said Kvitova who was off the tour for six months past year after suffering knife wounds fighting off a burglar at her home in the Czech Republic.
The 36-year-old got off to a winning start in straight sets over Kristyna Pliskova. Both are huge servers, but Pliskova leads the WTA tour with the record for most aces in a match (31).More news: Justin Timberklake meets with Santa Fe victims
There was a little rust to shake off on her return but all the same Serena was too strong, and too good, for her world 70-ranked opponent to set up a meeting with Australia's Ashleigh Barty in the next round.
Play has been interrupted at on Tuesday morning because of rain.
Williams, the victor of an Open era record 23 Grand Slam titles, had arrived at Roland Garros with just four matches under her belt in 2018.More news: UCF fans take issue with Las Vegas Golden Knights' national anthem twist