Showing no sign of the knee problems that sidelined him at the end of last year, Nadal yielded only eight points in six games in the first set. When Rochus finally got on the board while already down a break in the second, the capacity crowd in Rod Laver Arena gave him a huge ovation.
Nadal said he just wanted to get off to a good start and wasn't trying to send a message.
"I played well, especially the serve and the forehand," Nadal said.
Nadal, who reached the semifinals here last year and is seeking his sixth Grand Slam title, finished with 47 winners to just seven for Rochus and also blasted 10 aces. The 75th-ranked Belgian, who fell to 13-31 in Grand Slam play, managed to laugh several times, realizing there was little he could do.
Nadal broke for the seventh time to pull ahead 5-2 in the final set, then held at love with four winners to finish off the victory in 77 minutes.
Rochus suggested that he might need to consider a change in professions. Nadal said it's too dangerous to show any mercy.
"Sport is like this," Nadal said. "If I had some mistakes ... anything can happen."
Conditions were perfect for the last match of the night, a sharp contrast to the brutal sun and swirling winds that plagued players earlier in the day.
"I would have liked to have been on court a bit longer," said the fourth-seeded Murray, who won for the first time on center court here. "You don't want to win a match like that."
Most everybody else was eager to finish fast with the temperature topping 104 degrees in the afternoon. Murray, a 21-year-old Scot, said he could feel his feet burning on long points. Photographers at courtside draped their heads, bodies and cameras in wet towels. Spectators fanned themselves with paper and official programs.
Murray was installed as the favorite or joint favorite for the tournament by British bookmakers after beating Roger Federer three times since losing the U.S. Open final -- his best run at a major to date.
"I'm aiming to go one better here and I need all the support I can get," he said, noting the number of Scottish flags unfurled around the stadium. "It's nice. Hopefully they'll keep coming throughout the tournament."
In other men's matches, No. 5 Jo-Wilfried Tsonga beat Argentina's Juan Monaco, No. 6 Gilles Simon downed Spain's Pablo Andujar, and fellow Frenchman Richard Gasquet, seeded 24th, ousted Diego Junqueira.
Tsonga had upset wins over Murray in the first round and Nadal in the semifinals here last year before losing the final to Novak Djokovic.
Ninth-seeded James Blake, who reached the quarterfinals at Melbourne Park last year to match his best effort at a Grand Slam, had more than twice as many winners as unforced errors while beating Canada's Frank Dancevic.
No. 13 Fernando Gonzalez of Chile, runner-up here to Federer in 2007, ended local hope Lleyton Hewitt's 13th Australian Open. Hewitt, a former U.S. Open and Wimbledon champion, lost the final at his home major in 2005 to Marat Safin.
Information from The Associated Press and Reuters was used in this report.