MELBOURNE, Australia — Roger Federer shanked a few shots and was unsettled by how nervous he felt after six months on the sidelines, despite the familiar surroundings at the Australian Open.
No other man on tour knows the way around a Grand Slam tournament better than Federer, who is playing in his 69th major and has won a record 17.
He served 19 aces and had only one double-fault in a 7-5, 3-6, 6-2, 6-2 win Monday over fellow 35-year-old Jurgen Melzer, but dropped serve three times and experienced frustrating moments.
"I was feeling nervous once the match actually started," said Federer, who hadn't played at tour level since Wimbledon after taking time off to let his injured left knee heal. "In the warmup ... I felt fine. Then I hit four frames in a row. It was like, 'Whew, it's not as easy as I thought it was going to be.'
"I struggled for a while to find that groove, that rhythm."
Federer had surgery on the knee after a semifinal exit at the last Australian Open and missed the French Open, ending his streak of 65 consecutive Grand Slam tournaments. He returned for Wimbledon, reached the semifinals, then didn't play again in 2016. In November, he fell out of the top 10 for the first time in 734 weeks.
The 17th-seeded Federer wasn't the only highly-ranked player to find the going tough Monday.
Stan Wawrinka, the U.S. Open champion, was pushed to five sets. So was No. 5-seeded Kei Nishikori. Angelique Kerber, defending champion and ranked No. 1 at a major for the first time, had some nervous moments in her 6-2, 5-7, 6-2 win over Lesia Tsurenko.
Kerber won her first Grand Slam title in Melbourne last year, beating Serena Williams in the final after saving a match point in the first round.
After wasting a match point before her serve was broken as Tsurenko rallied to win the second set, Kerber said her mind raced back 12 months.
"When I lost the second set, and I had match point, I was thinking about my match last year in the first round," she said. "First rounds are always tough."
In his first Grand Slam match with the elevated status of having a knighthood and the No. 1 ranking, Andy Murray berated himself when he made mistakes and frequently yelled during a 7-5, 7-6 (5), 6-2 win over Illya Marchenko.
In other words, nothing much has changed.
The five-time finalist comfortably navigated what he hoped was the first step to a drought-breaking Australian Open title.
Murray has lost four of the last six finals in Melbourne to six-time champion Novak Djokovic.
Gaining the top ranking and receiving the civic honors doesn't change anything for Murray, who said he faces "the same pressure, same expectations. I've never won here — I'm going to try to change that this year."
Wawrinka, who made his Grand Slam breakthrough in Australia in 2014, narrowly scraped past 35th-ranked Martin Klizan 4-6, 6-4, 7-5, 4-6, 6-4.
In the ninth game of the fifth set, Wawrinka smashed a soft half-volley from Klizan straight back into the Slovakian's body, clipping the frame and just missing his midsection. He stepped over the net and ensured Klizan was OK, then held serve in that game and broke in the next game to finish it off.
Nishikori beat Andrey Kuznetsov 7-5, 1-6, 6-4, 7-6 (6), 6-2. Joining him in the second round are 2014 U.S. Open champion Marin Cilic, 2008 Australian Open finalist Jo-Wilfried Tsonga, No. 19 John Isner, No. 23 Jack Sock, No. 27 Bernard Tomic, No. 29 Viktor Troicki and No. 31 Sam Querrey.
Also, No. 14 Nick Kyrgios returned from his suspension for underperforming in Shanghai last year and raced through a 6-1, 6-2, 6-2 win over Gastao Elias.
No. 16 Lucas Pouille was the highest-ranked of the three men's seeded players to lose.
Five of the women's seeded players went out, including No. 4 Simona Halep, who lost 6-3, 6-1 to Shelby Rogers in the first match on Rod Laver Arena, and No. 15 Roberta Vinci, who lost to CoCo Vandeweghe.
Seven-time major winner Venus Williams beat Kateryna Kozlova 7-6 (5), 7-5, and 2014 Wimbledon finalist Eugenie Bouchard continued her recent resurgence by routing Louisa Chirico 6-0, 6-4.
Joining them in the next round will be French Open champion Garbine Muguruza, Olympic gold medalist Monica Puig, No. 8 Svetlana Kuznetsova, No. 10 Carla Suarez, No. 11 Elina Svitolina and No. 20 Zhang Shuai.
Sixteen-year-old Destanee Aiava became the first player born in this millennium to play in the main draw of a major, but the milestone match ended in a 6-3, 7-6 (4) loss to Mona Barthel.