The show went on at the world's most-celebrated Carnival parades, despite a tropical deluge that soaked thousands of feather-clad dancers, wildly costumed musicians and masses of spectators at Rio de Janeiro's Sambadrome.

The skies opened up about an hour before the start of the all-night extravaganza on Sunday, drenching revelers, flooding streets near the Sambadrome and even the walkways within Rio's Mecca of Carnaval.

Tennis star Rafael Nadal, in town for the Rio Open, took part in the opening parade of the night, covered by a plastic rain slicker.

Mobbed by the media, the Spaniard stayed for only about 20 minutes, trying out fancy footwork meant to resemble samba dancing and posing for selfies along with Brazil's former French Open winner Gustavo "Guga" Kuerten.

This year's five-day Carnival celebrations, which also include about 450 alcohol-soaked street parties, come as a welcome respite from the recent avalanche of bad news afflicting Brazil.

In addition to near-constant reminders of the stalled economy, Brazilians are coping with a snowballing corruption scandal at state-run oil giant Petrobras as well as the worst drought in 80 years in the southeast, which includes Rio and the country's industrial and business hub of Sao Paulo.

Carnival celebrations in smaller cities have even been canceled because of the drought.

Sunday's rains in Rio were welcomed widely, despite interfering with the city's biggest party.

"It hasn't dampened the performers' spirits, and at least it's not so hot with the rain," said Helio Abreu, a 53-year-old doctor taking shelter with his wife at a concession stand.

In Paraty, a colonial jewel of a city between Rio and Sao Paulo, celebrations were scaled down after a deadly shooting on Saturday night.

One person was killed and nine others injured, including three tourists from Sao Paulo. The incident happened amid a crowd of revelers in the historic downtown area, news reports said.

Six samba schools paraded in Rio's Sambadrome on Sunday night, with each group required to get its thousands of participants and giant floats across the 730-meter-long runway in under 82 minutes.

Six other schools were due to perform on Monday, with all 12 groups vying for the title of the year's best.