The seven-time champion made her first playing return to Centre Court since 2016 and eased past Bulgarian Viktoriya Tomova 6-1 6-4.

Williams is still working her way back up to full speed following the birth of her daughter last year, but is already looking a threat at the tournament.

“There’s so many things that I want to improve on, but that’s kind of how I always feel,” she said.

“I feel like I’m going in the right direction. This match was better than my first round. I just hope every match is better.

“I served a little more consistent. I still want to work on getting my first serves in more. Overall it’s definitely a little bit better than the first round.”

Second seed Caroline Wozniacki became the highest-ranked casualty of the tournament so far as she lost to Ekaterina Makarova.

The Dane, who won the title in Eastbourne last week, lost 6-4 1-6 7-5 to the Russian on Court One, meaning half of the top 10 seeds have already been dumped out in the opening two rounds.

Wozniacki, who was also troubled by flying ants, said: “I think I did everything I could. I fought as hard as I could. I can’t even be mad at myself because I played up to the level that I can.

“I think she played above her level and really raised it and got a little lucky and played well when she needed to.”

Venus Williams overcame a scare to book her place in the third round.

The 2017 runner-up and five-time former champion came from a set down to beat Alexandra Dulgheru 4-6 6-0 6-1. She was sloppy in losing the opening set but got her act together.

Madison Keys celebrated Independence Day by beating Thailand’s Luksika Kumkhum as she recorded a 6-4 6-3 victory but British hope Katie Swan’s run was emphatically ended by 29th seed Mihaela Buzarnescu.

Croatian Donna Vekic followed up her toppling of fourth seed Sloane Stephens with a 7-5 6-4 win over Rebecca Peterson while Agnieszka Radwanska went out to Lucie Safarova.

Meanwhile, Roger Federer has considered visiting the Wimbledon queue to hear the stories of his fans who are camping out in hope of seeing him play.

Even by @rogerfederer's standards, this drop shot was one of his finest 👏#Wimbledon pic.twitter.com/KtCYN0yxxI

— Wimbledon (@Wimbledon) July 4, 2018

Thousands of spectators line up every year desperate to get their hands on tickets for the main show courts and a vast number of them are Federer fans. Those who were lucky enough to get a seat on Centre Court on Wednesday saw the defending champion put on a scintillating display as he destroyed Slovakia’s Lukas Lacko 6-4 6-4 6-1 in just 90 minutes.

The performance would have made a couple of nights in a tent worth it even if a visit from the man himself did not materialise.

“Every time when I see an article or a video, especially which I enjoy a lot, I see something about the queue, I hear what they say, how excited they are about Wimbledon,” he said. “They get asked, ‘Who are you here to see?’. Your name drops, it’s always very exciting, I must tell you.”