MELBOURNE, Australia -- A self-admitted "rusty" Novak Djokovic began his bid for a fourth consecutive Australian Open title with a 6-3, 7-6 (2), 6-1 win Monday over Lukas Lacko. Serena Williams appeared to be as polished as ever in beating Australian teenager Ashleigh Barty.
With his new coach and six-time Grand Slam singles champion Boris Becker watching him during an official match for the first time, Djokovic appeared tentative early against the Slovakian player, who often appeared content to keep the ball in play.
But as the second-seeded Djokovic's patience level began to drop, his skill level stepped up. He stayed on course for a fifth Australian title, hoping to be the first man to achieve that feat since the Open Era began in 1968.
Top-ranked Williams won her 23rd consecutive match -- including 18 at the end of last season and four last week in winning the Brisbane International -- after beating Barty 6-2, 6-1 in 57 minutes.
Williams continues to be in rarified territory. Her Brisbane title was the 58th of her career -- she won 11 last year, including the French Open and U.S. Open. A five-time winner of the Australian Open, she's trying to end Victoria Azarenka's two-year run as women's champion at Melbourne Park.
"Obviously I'd love to win again in Melbourne," Williams said.
Djokovic also had a strong finish to 2013, entering the tournament on a 24-match winning streak, which followed his loss to Rafael Nadal in last year's U.S. Open final. He's now also on a 22-match winning streak at Melbourne Park.
"It is the first competitive match I've had this season, I haven't played for five or six weeks," Djokovic said. "I was a bit rusty on the court the first two sets. Afterwards it was all working well."
Serena's sister, Venus Williams, started well earlier Monday but unforced errors in two key periods in her match sent the seven-time major winner out of the tournament.
The elder Williams missed a break-point chance in the sixth game and then, after getting to 40-30 on serve in the ninth, inexplicably fired three consecutive double-faults to surrender a break and just about the set to No. 22-seeded Ekaterina Makarova.
She took a 3-0 lead in the third before her unforced error toll climbed to 56 and Makarova won six of the next seven games for a 2-6, 6-4, 6-4 win.
The 33-year-old Venus Williams, the second-oldest player in the tournament, has struggled with injuries and illness in recent seasons but reached the final of the WTA event at Auckland to start 2014 and came to Melbourne saying she was feeling better than she had in years.
"The last 12 months I have had issues," she said. "But this year I definitely am looking forward to having a good run and feeling well."
Three-highly-ranked players were beaten in the first round, including 2011 Wimbledon champion Petra Kvitova and two Italians, No. 7 Sara Errani and No. 12 Roberta Vinci.
Sixth-seeded Kvitova lost 6-2, 1-6, 6-4 to No. 88-ranked Luksika Kumkhum of Thailand, who was playing in just her second Grand Slam tournament.
Errani, the 2012 French Open finalist, was beaten 6-3, 6-2 by Julia Gorges of Germany and Vinci lost 6-4, 6-3 to Zheng Jie of China.
Two-time finalist Li Na beat Ana Konjuh of Croatia -- the youngest player in the tournament -- 6-2, 6-0. Other winners were Wimbledon semifinalist Kirsten Flipkens, beating Britain's Laura Robson, No. 9 Angelique Kerber, 2011 U.S. Open champion Sam Stosur, No. 14 Ana Ivanovic, No. 26 Lucie Safarova, No. 28 Flavia Pennetta, No. 30 Eugenie Bouchard and No. 31 Daniela Hantuchova.
American Madison Keys wasted five match points in the second set and another in the third before beating Patricia Mayr-Achleitner of Austria 6-2, 6-7 (8), 9-7.
Third-ranked David Ferrer opened with a 6-3, 6-4, 6-4 win over Colombia's Alejandro Gonzalez and No. 7 Tomas Berdych beat Aleksandr Nedovyesov of Ukraine 6-3, 6-4, 6-3. No. 20 Jerzy Janowicz, a semifinalist at Wimbledon last year, rallied to beat 19-year-old Australian wild card Jordan Thompson 1-6, 4-6, 6-4, 6-2, 6-1 in 3 hours, 16 minutes.
Other men advancing included No. 9 Richard Gasquet, No. 14 Mikhail Youzhny, No. 17 Tommy Robredo, No. 19 Kevin Anderson, No. 23 Ernests Gulbis, No. 29 Jeremy Chardy, No. 32 Ivan Dodig and American Sam Querrey, who defeated Santiago Giraldo of Colombia, 6-3, 6-2, 3-6, 7-6 (3).
On Tuesday, in the tougher top half the men's draw, top-seeded Rafael Nadal, Wimbledon champion Andy Murray and Roger Federer are all in action.