The two-time grand slam champion has a fond association with the harbour city, having won four Sydney Internationals and countless Davis Cup ties on Ken Rosewall Arena, but says the Olympic Park tennis facility is outdated and deserves an overdue refurbishment.

Earlier this week the ATP told Fairfax Media it was strongly considering Australia as the host for its revamped World Team Cup, but that Sydney's lack of a world-class tennis arena could harm the country's proposal to stage the event.

A start date of 2020 has been slated for the expanded World Team Cup, which hasn't been played since 2012, giving the NSW Government two years to address the issue.

The government undertook a feasibility study on Sydney's indoor facilities last year, and concluded the city needed a world-class venue that could host a range of sports, as well as concerts. A timeframe for when such a venue would be constructed has not yet been publicly announced.

While that could cost an estimated $400m, a temporary measure to help Australia secure the tournament would be an immediate upgrade to the tennis facilities at Sydney Olympic Park, including putting a roof over Ken Rosewall Arena, and upgrading corporate and player facilities.

"The centre was done obviously for the Olympic Games which is 18 years ago now," Hewitt said.

"It could use a bit of a touch up to modernise it a bit more, possibly even have another show court out there that's slightly bigger as well as a retractable roof on the centre court.

"To host those bigger events, that's what you need moving forward. There's been other stadiums out at Homebush that I believe are getting a bit of a redevelopment out there as well and tennis, I think it's about time that they got it.

"Sydney's been a fantastic place to play tennis over the years, I've always loved playing the [Sydney International] tournament but also Davis Cup ties out at Homebush as well. As one of our biggest cities in Australia, I think it deserves that."

The weather has been kind enough to Sydney International organisers this week, and only a handful of matches have been delayed.

One of them was on Tuesday night when drawcard Venus Williams was forced to wait two hours while it rained, before ultimately losing her match to eventual women's finalist Angelique Kerber. By the time she was back out on court it was very late into the evening, and only 400 hardy souls remained at the venue.

Alex de Minaur's quarter-final match against Feliciano Lopez was also delayed momentarily on Thursday night due to rain.

Not only does the lack of a roof delay tennis matches when it rains, it makes Sydney a less attractive proposition for television broadcasters who need a guarantee of content.

Hewitt used to play in the World Team Cup in Germany when it was a much smaller tournament leading into the French Open, but the ATP envisages a much larger event from 2020 involving 24 teams and the world's best players.

It has been slated as the biggest event on the tour outside of a grand slam, and Australia is the logical choice as host given it could be staged in the two weeks prior to the Australian Open.

"To be able to hold such a signature event, with the best male players coming to represent their country in that kind of format would be pretty amazing," Hewitt said.

"I played the old World Team Cup when it used to be played as a lead-in to the French Open, it was on clay.

"This is going to be basically a modernised version of that on a lot bigger scale. It'd be pretty cool to have it in our country for the first time."