Michael Phelps, the most decorated Olympian of all time, is fired up and ready to go for what promises to be an explosive first weekend of the Rio Olympic swimming programme.

Since Sydney 2000, the US swimmer has bagged 18 Olympic gold medals - and he's back for one final swansong at Rio 2016, giving himself a chance to win four more.

The 31-year-old was his country's flag-bearer at the opening ceremony and is taking part in his fifth Olympic Games.

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Along with competing in the 100- and 200m butterfly and 200m individual medley, Phelps could also feature in Sunday's 4x100 freestyle relay final.

The US team has not failed to finish in the top three since the event was introduced in 1964, but champions France and resurgent Australia will be tough opponents.

"The first two nights of the relays, with the women's on the first night and the men's on the second, there will probably be a lot of fireworks in the swimming pool," said Phelps.

"I'm looking forward to either watching or being in that race. Those races are ... super fast and there are always some crazy splits that take place.

"I think this sport has changed to where there's not really one or two powerhouses," said Phelps.

"You could probably pick three or four teams that are going to have a chance to win that [men's] relay."

Source: Al Jazeera and agencies