Nadal was in ominous form as he dropped just three games on his way to thrashing Burgos 6-1, 6-1, 6-1 on the Rod Laver Arena court.

The victory for the Spaniard, and the method in which it came, allayed any concerns over his fitness after he missed the Brisbane International earlier this month due to a knee injury he sustained in November.

"If I did not feel ready I would not be here and I'm happy to be back," the 2009 winner said.

"I always have doubts, but at the same time I have confidence that I was ready to start the tournament and that was the case."

Men's third seed Grigor Dmitrov of Bulgaria, the winner of last year's World Tour Finals, booked his place in round two with a 6-3, 6-2, 6-1 success over Austrian Dennis Novak.

Jack Sock of the US, seeded sixth, was among the highest-profile casualties on day one as he was beaten 6-1, 7-6, 5-7, 6-3 by Japan's Yuichi Sugita.

It proved to be a difficult start to the tournament for the American team as Venus Williams also crashed out after losing 6-3, 7-5 to Switzerland's Belinda Bencic.

"It means so much to me," Bencic told BBC Radio 5 live.

"I lost to Venus four times and I tried my best to give my all today, and changed some things tactically.

"I think it was a huge opportunity and I used it, so I was very relieved after the match point. 

"After the injury and the tough times it's really an amazing feeling."

US Open winner Sloane Stephens suffered an early exit as she was on the end of a shock 2-6, 7-6, 6-2 defeat to China's Zhang Shuai.

Coco Vandeweghe, the 10th seed, is also out after she lost 7-6, 6-2 against Hungarian Tímea Babos.