MELBOURNE, Australia (AP) — As a first-time dad with a baby at home, Novak Djokovic could see merits in the tale of Serena Williams’ mid-match espresso that has been brewing in the lead-up to the Australian Open.

Hey, he reckons, why not open up the menu?

The No. 1 seeds in the men’s and women’s draws both had straight-set wins in their first-round matches on Tuesday. Djokovic shrugged off the effects of a cold to beat No. 116-ranked Aljaz Bedene 6-3, 6-2, 6-4 in his first Grand Slam match as a father, and Williams beat No. 106-ranked Alison Van Uytvanck 6-0, 6-4.

Williams, with five Australian titles in her collection of 18 majors, didn’t need anything to perk her up as she raced through the first set in 21 minutes. It was a vastly different story when she arrived in Australia, jet-lagged, this month to start her preparations for the season’s first major, and asked for a coffee during a Hopman Cup match in Perth.

She checked with the chair umpire and tournament referee first, because she didn’t know if she could order a brew. The coffee was served, and Williams rallied for a win.

“Judging by what she did, it opens up a new chapter of rules I guess on the tennis court,” Djokovic said. “Maybe we need to explore more. Some people can’t live without coffee in the morning, it keeps them going. I guess that helped her in that match.”

Djokovic has left his wife and baby son — Stefan, who was born in October — at home as he bids for a fifth title at Melbourne Park. He was sick on the weekend, and missed some practices.

“It hasn’t been an ideal couple of weeks in terms of health and preparation,” he said. “But I fought my way through. Now it’s behind me.”

Djokovic won the first of his Australian Open titles in 2008, then three in a row from 2011. But his 25-match winning streak at Melbourne Park ended in a quarterfinal loss last year to eventual champion Stan Wawrinka.

That led to a breakout year for Wawrinka that included his first major, a rise to No. 3 in the rankings, and a Davis Cup title with Switzerland.

Seeded fourth, he began the defense of a major for the first time with a 6-1, 6-4, 6-2 win over No. 100-ranked Marsel Ilhan.

“It’s great, bringing me a lot of memories from last year,” Wawrinka said of his return. “It was great to come back here feeling happy, happy with my game.”

U.S. Open finalist Kei Nishikori and Wimbledon semifinalist Milos Raonic are part of the next generation of serious major contenders, and both opened their campaigns well.

No. 5 Kei Nishikori beat Nicolas Almagro 6-4, 7-6 (1), 6-2, and No. 8 Raonic fired 30 aces in a 7-6 (3), 7-6 (3), 6-3 win over Illya Marchenko. No. 9 David Ferrer, a quarterfinalist or better at the last four Australian Opens, also advanced.

The 33-year-old Lleyton Hewitt started his 19th consecutive Australian Open with a four-set win in a night match, while Vasek Pospisil beat Sam Querrey 6-3, 6-7 (5), 2-6, 6-4, 6-4, and No. 17 Gael Monfils rallied from two sets down, and from a break down in the fifth, to beat fellow Frenchman Lucas Pouille 6-7 (3), 3-6, 6-4, 6-1, 6-4.

Wimbledon champion Petra Kvitova and No. 6 Agnieszka Radwanska advanced, along with 2014 Australian finalist Dominika Cibulkova, two-time champion Victoria Azarenka, and No. 18 Venus Williams. No. 12 Flavia Pennetta, No. 13 Andrea Petkovic and No. 15 Jelena Jankovic were all eliminated.

Azarenka, coming back from a foot injury, beat Sloane Stephens 6-3, 6-2 — her third win in three years over the American at the Australian Open — and will next have to play U.S. Open finalist Caroline Wozniacki.

Serena Williams has only ever lost once in the first round of a major — she’s playing her 58th.

Inevitably — she played in a bright dress that revealed her lower back — there was the question on fashion.

It’s part of her plans to have fans and rivals looking at her back all year, although she thinks there might have to be some modifications if more order-in deliveries are allowed.

“I don’t know what’s allowed. A hamburger, French fries,” she said, “Yeah, I love eating pizza. I can’t have it this (tournament). I don’t want to break my dress.”