A lead-up to the Australian Open, the 24-team ATP Cup offers $22 million in prizemoney and has attracted nine of the world's top-10 players and 26 of the top 30.

Starting on January 3, early rounds will be played in Brisbane and Perth, with the final being held in Sydney on January 12.

Now a dual US-Australian citizen, Macpherson said he was honoured to be given the role of on-court captain for the American team.

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"It will be a first for me," Macpherson said.

"I've been off-court doubles adviser for the US Davis Cup team on numerous occasions and I also had that role with Roger Federer and Stan Wawrinka when Switzerland won the Davis Cup, but this will be the first time I've been on-court captain in a major team event.

"I'm really excited about it and determined to do the best I can for the team."

Macpherson, who coaches the US' no.1 singles player John Isner, said the ATP Cup had attracted far more of the world's best players prior to the Australian Open than the previous minor tournament lead-up format.

"It's unfortunate that Roger Federer won't be there but basically all the rest of the superstar players including Novak Djokovic, Rafael Nadal and Dominic Thiem are playing. The fans will love it."

Season 2020 will also have a sentimental aspect for the Tasmanian as the game's most successful doubles pair in history - American twins, Mike and Bob Bryan - complete their farewell year.

Macpherson has coached the brothers for the past 12 years.

"There have been so many great moments with Bob and Mike, their Olympic gold medal, 16 grand slams, Davis Cup wins. Their retirement will see the end of an amazing era in doubles that may never be equalled,'' Macpherson said.

"Bob and Mike are loved by fans everywhere they go for their brilliant doubles skills and sportsmanship."

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