World number one Rafael Nadal powered into the Australian Open second round with a routine win over the Dominican Republic’s Victor Estrella Burgos.
The Spaniard, who had not played a tournament match since suffering a knee injury in November, won 6-1 6-1 6-1.
“I’m very happy to be back, it’s a very important beginning for me,” he said.
Third seed Grigor Dimitrov and in-form Australian Nick Kyrgios also advanced, but eighth seed Jack Sock was one of 10 American men and women to lose.
Sock went down 6-1 7-6 (7-4) 5-7 6-3 to world number 41 Yuichi Sugita, and 16th seed John Isner lost 6-4 3-6 6-3 6-3 to Australia’s Matthew Ebden.
Fifth seed Venus Williams, 10th seed Coco Vandeweghe and US Open champion Sloane Stephens were all knocked out of the women’s event.
Nadal impresses with rapid victory
Nadal, aiming for a 17th Grand Slam title and a second in Australia, was hampered by a knee injury at the end of the 2017 season.
It forced him to miss this month’s Brisbane International, and he only had a one-match workout at the exhibition Kooyong Classic before heading into the first Grand Slam event of the year.
But the Spaniard, who was beaten by Roger Federer in last year’s final, got off to a perfect start and raced to victory over the 37-year-old in 94 minutes on Rod Laver Arena.
The world number one will play Leonardo Mayer of Argentina next.
What else happened on day one?
Bulgarian Dimitrov, 26, went through with a 6-3 6-2 6-2 win over Austrian Dennis Novak in one hour 38 minutes.
Kyrgios, the top-seeded Australian in the men’s draw at 17, enjoyed a straightforward 6-1 6-2 6-4 victory over Brazil’s Rogerio Dutra Silva.
Croatia’s sixth seed Marin Cilic beat Canadian qualifier Vasek Pospisil 6-2 6-2 4-6 7-6 (7-5).
Women’s second seed Caroline Wozniacki recorded her 101st Grand Slam victory, beating Romanian Mihaela Buzarnescu 6-2 6-3.
And fourth seed Elina Svitolina of Ukraine, winner of the Brisbane International, saw off Serb qualifier Ivana Jorovic 6-3 6-2.
Who to watch on day two
Britain’s Johanna Konta and Heather Watson play on day two, as do men’s champion Roger Federer, former winners Novak Djokovic and Maria Sharapova and women’s top seed Simona Halep.
Source: BBC