The all-star cast of the inaugural United Cup has received another boost, with the announcement of several former and current WTA and ATP champions as team captains.

Former World No.2 Agnieszka Radwanska will co-captain the Polish team with husband (and Billie Jean King Cup captain) Dawid Celt, while 1997 Roland Garros champion Iva Majoli will take charge of the Croatian team.

United Cup: Who's playing and where?

Samantha Stosur and Kirsten Flipkens will both take on dual roles as playing captains for Australia and Belgium respectively. Stosur and Flipkens have both retired from singles, but remain active in doubles and have already been nominated on their teams. Stosur, the 2011 US Open champion, will co-captain Team Australia with former ATP No.1 Lleyton Hewitt.

Former doubles World No.1 Gisela Dulko rounds out the current and former WTA players named as captains. Dulko, the 2011 Australian Open doubles champion with Flavia Pennetta, will captain Team Argentina.

Iva Majoli in her role as Billie Jean King Cup captain during the 2022 play-offs with Petra Martic.

Nel Pavletic/Pixsell/MB Media/Getty Images

Two WTA coaches will also double as team captains. Jiri Vanek, the coach of Petra Kvitova, will captain the Czech Republic's team, while Jessica Pegula's coach David Witt will take on Team USA.

Further team captains include former ATP players Tim Henman (for Great Britain) and Christian Ruud (for Norway). There will also be four ATP playing captains: three-time Grand Slam champion Stan Wawrinka for Switzerland, 2014 Roland Garros doubles champion Edouard Roger-Vasselin for France, Grigor Dimitrov for Bulgaria and Alexander Bublik for Kazakhstan.

The United Cup will kick off the 2023 season on Dec. 29 in Brisbane, Perth and Sydney, which will host the tournament's group stages before the semifinals and final are played in Sydney. Seventeen of the 18 teams in the mixed WTA and ATP event have named their captains, with only Greece remaining. For the full roster of teams and captains, click here.