MELBOURNE, Australia (AP) — If Rafael Nadal gave the Australian Open a throwback feel last year with his straight-out-of-the-mid-2000s final against Roger Federer, he's completed the retro effect this year with a return to his sartorial roots — a sleeveless T-shirt.

Matching the muscle-exposing Nike tank top with neon pink shorts, wristbands and headband, Nadal also found his championship form again in a 6-1, 6-1, 6-1 rout of 37-year-old Victor Estrella Burgos in the first round at Melbourne Park.

The top-ranked Spaniard, who made a splash as a teenager with his trademark sleeveless shirts and knee-length pirate pants, came into this year's Australian Open with questions about his health and readiness to compete following a taxing season that saw him capture two Grand Slams and return to No. 1.

Nadal had been forced him to withdraw from the ATP Finals in November due to a lingering right knee injury, and when the pain persisted, he also pulled out of a season-opening exhibition event in Abu Dhabi and his first tournament in Brisbane.

With only a few exhibition matches last week to test his form, Nadal had doubts he'd be ready to go in time for the first major of the year. But a dominant performance against Estrella Burgos — he had 28 winners and saved five of six break points he faced — left him feeling positive about his start in Melbourne.

"If I don't feel myself ready, I will not be here. So I am happy to be here, happy that I'm on court again," he said.

With several top seeds falling on the women's side, including 2017 Australian Open finalist Venus Williams and U.S. Open champion Sloane Stephens, the men's draw was largely spared similar upsets.

Third-seeded Grigor Dimitrov advanced with a routine 6-3, 6-2, 6-1 win over qualifier Dennis Novak, while No. 6 Marin Cilic topped Vasek Pospisil 6-2, 6-2, 4-6, 7-6 (5) and local favorite Nick Kyrgios looked sharp in a 6-1, 6-2, 6-4 victory over Rogerio Dutra Silva.

"Obviously I know I'm hitting the ball well," Kyrgios said. "But to go out there in front of the crowd again, just trying to play well, I was a bit nervous going out there. (I'm) happy to get through."

No. 10 Pablo Carreno Busta, No. 23 Gilles Muller, No. 24 Diego Schwartzman, No. 28 Damir Dzumhur, No. 30 Andrei Rublev and No. 31 Pablo Cuevas also advanced.

No. 8 Jack Sock, No. 11 Kevin Anderson and No. 16 John Isner were among the losers.

For Sock, who lost to Yuichi Sugita 6-1, 7-6 (4), 5-7, 6-3, it was a disappointing result given the impressive way he finished last season with a maiden Masters win in Paris and a first-time appearance at the ATP Finals. He came to the Australian Open sporting a career-high ranking of No. 8 and his highest-ever seed at a major.

The American said, however, that he felt the same as Nadal after a lengthy 2017 — physically spent and lacking enough of an off-season to recover fully.

"It's just a weird feeling because you're just on the highest of highs after making it (to the ATP Finals)," he said. "And then it's back to reality and the grind of it."

Like Nadal and other top players, he said he's going to be smarter about his schedule now that he's among the elite on the tour.

His goal for 2018? "Win a match would be a good start," he deadpanned.