Just like defending women's champion Petra Kvitova in the match before him, Nadal had a shaky start Tuesday on Centre Court. He was two points away from going down 5-0 in the first set, but Bellucci netted an overhead backhand at 30-15 and Nadal went on to break for 4-1 to start the comeback. He won the next three games to make it 4-4 and Bellucci then self-destructed in the tiebreaker, making several unforced errors.
The two-time champion was hardly troubled after that and served out the match with an ace.
"I'm very happy to be back on the best court in the world and winning," Nadal said. "It's fantastic for me, but I have to improve a lot for the next round."
Nadal, coming off his record seventh French Open title, broke six times and had 35 winners and 18 errors. Having lost in last year's final to Novak Djokovic, he is bidding for a 12th Grand Slam title.
Earlier Tuesday, playing his first match since having a medical procedure on his heart, Mardy Fish of the United States hit 24 aces and beat Ruben Ramirez-Hidalgo of Spain 7-6 (3), 7-5, 7-6 (1) at Wimbledon on Tuesday to reach the second round.
Afterward, Fish canceled his news conference, because "he's not feeling well," ATP spokesman Nicola Arzani said. Fish told ESPN's Tom Rinaldi, via text message, that he was not feeling well and needed to lie down, but that the issue was "not heart related."
The 30-year-old Fish hadn't played a competitive match in 2½ months, taking time off because of an accelerated heartbeat.
Hours after losing a match at Key Biscayne, Fla., on March 29, Fish went to be checked by doctors after his heart started racing at night, and he pulled out of the U.S. Davis Cup team's quarterfinal against France the following week.
In May, doctors induced extreme palpitations to try to pinpoint the problem.
Fish reached the quarterfinals at Wimbledon last year, his best showing at the grass-court tournament.
Against Ramirez-Hidalgo -- at 34, the oldest man in the field -- Fish played his usual brand of attacking, serve-and-volley tennis. His serves topped 130 mph and he wound up with 61 winners, 43 more than Ramirez-Hidalgo.
Play was later suspended for the day because of rain and poor light, leaving several matches unfinished. Three-time finalist Andy Roddick was leading Britain's Jamie Baker 7-6 (1), 4-2 on Court 1 when the covers came on.
Murray took control from the start and never looked back against the former third-ranked Russian. Murray broke Davydenko six times and never dropped his own serve.
As always, Murray is facing high expectations from the home crowd that he can become the first British man to win Wimbledon since Fred Perry in 1936.
Hewitt was playing as a wild card for the first time at Wimbledon and couldn't stop the sixth-ranked Frenchman, who broke once in each set to win 6-3, 6-4, 6-4. Tsonga finished with 61 winners to the Australian's 12.
Tsonga reached the semifinals at the All England Club last year after rallying from two sets down against Roger Federer in the quarterfinals, before losing to eventual champion Djokovic. Tsonga lost to Djokovic again at the French Open this year after holding four match points in their quarterfinal.
Hewitt was playing in his 14th straight Wimbledon. He had not lost in the first round since 2003, when he was the defending champion. He was one of four Australians in the men's draw, and all bowed out in the first round. It marks the first time since 1938 that no Australian men have reached the second round at Wimbledon.
"The boys didn't have the best day," said Hewitt.
In a men's match between two rising stars, 21-year-old Belgian wild card David Goffin -- who reached the fourth round of the French Open and took a set off Federer -- rallied from a set down against 19-year-old Bernard Tomic to beat the 20th-seeded Australian, 3-6, 6-3, 6-4, 6-4.
Levine, a 24-year-old based in Boca Raton, Fla., has practiced and trained with Federer.
"I know he's been playing some serious tennis lately," Levine said about Goffin. "It's going to be a tough match. A guy like Goffin is going to be able to come up with some big shots at crucial times."
Information from The Associated Press contributed to this report.