Roger Federer picked up where he left off at the last Australian Open on a day when Maria Sharapova, Angelique Kerber and Novak Djokovic ensured there were all kinds of successful comebacks.
Defending champion Federer beating Aljaz Bedene 6-3, 6-4, 6-3 in a night match, his first on Rod Laver Arena since clinching a career-reviving title here last year. He's been met on court after wins here previously by tennis greats Laver, John McEnroe and Jim Courier.
One of just two former champions in the women's draw, Sharapova recovered from an early break in the second set and closed out her 6-1, 6-4 victory over Tatjana Maria with an ace at Margaret Court Arena.
She celebrated by twirling, waving and blowing kisses to the crowd.
"It's been a couple of years since I've been back here — obviously I wanted to enjoy the moment," the 2008 Australian Open champion and three-time runner-up said in an on-court TV interview. "It was really meaningful for me to be out here."
Kerber, the 2016 champion, continued her resurgent run with a 6-0, 6-4 win over fellow German Anna-Lena Friedsam. It extended her streak to 10 consecutive wins, including the Sydney International title last week — her first title since the 2016 U.S. Open.
Her ranking slid into the 20s in 2017, but she's coming back into the kind of form which makes her a title contender.
"I'm just enjoying it on court again," Kerber said. "Something is going on with Australia and me. I love this country — I enjoy my stay, play my best tennis."
Djokovic tweaked his service motion while recovering from an injured right elbow, and used it to good effect in a 6-1, 6-2, 6-4 win over Donald Young, who saved four match points on his own serve but was out in the next game.
Djokovic lost in the second round here last year, but won five of the previous six Australian Open titles.
"Obviously I wanted to start with the right intensity, which I have," Djokovic said. "I played perfect tennis, like I never stopped."
Wawrinka, who had six months out after surgery on his left knee, beat Ricardas Berankis 6-3, 6-4, 2-6, 7-6 (2).
No. 4-ranked 4-Alexander Zverev and No. 7 David Goffin advanced, but No. 20 Roberto Bautista Agut lost to fellow Spaniard Fernando Verdasco, a semifinalist here in 2009, and former Wimbledon finalist Milos Raonic lost 6-7 (5), 7-5, 6-4, 7-6 (4) to Lukas Lacko.
No. 13 Sam Querrey restored some order for the U.S. men with a 6-3, 6-4, 6-2 win over Feliciano Lopez. Two other U.S. contenders, No. 8 Jack Sock and No. 16 John Isner, were out on opening day.
Madison Keys also reversed a trend, becoming the only one of the four American women who contested the U.S. Open semifinals last September to reach the second round in Australia.
Sloane Stephens, Venus Williams and CoCo Vandeweghe were all eliminated on Monday.
No. 17-seeded Keys, the runner-up at the U.S. Open, had a 6-1, 7-5 win over Wang Qiang.
No. 9 Johanna Konta beat Madison Brengle 6-3, 6-1 and will meet another American, Bernarda Pera in the second round. The U.S. women had three wins and 14 losses in round one.
No. 1-ranked Simona Halep was in serious trouble twice — having to save set points at 5-2 down in the first set, and badly twisting her left ankle early in the second — before beating 17-year-old Australian wild-card entry Destanee Aiava 7-6 (5), 6-1.
Halep, who lost back-to-back first-round matches here in the previous two years, will next play Eugenie Bouchard, the 2014 Wimbledon finalist who beat Oceane Dodin 6-3, 7-6 (5).
"It's always really cool to go up against the best in the world," Bouchard said. "You use it as a measuring stick. I want to try to play my game and go out there and do some damage."
Other seeded players advancing included No. 6 Karolina Pliskova, No. 8 Caroline Garcia, No. 16 Elena Vesnina, and No. 29 Lucie Safarova.
Sharapova was banned for after testing positive for the drug meldonium here in 2016, when she reached the quarterfinals and finished last year ranked No. 60.
The five-time major winner could next meet No. 14-seeded Anastasija Sevastova, who beat her at the U.S. Open last year in her return to a Grand Slam to the tournament.
After returning in New York, Sharapova is confident she's prepared again for a major.
"I felt like I have got a lot of things out of the way physically and emotionally and mentally last year with — there was a lot of firsts again for me, playing the first tournament, first Grand Slam, and just different feelings and what it would be routinely," she said. "But it felt pretty routine today."
(With AP Inputs)