World No.4 Coco Gauff reckons she will have her hands full even if she fronts up against Australian Maya Joint instead of six-time grand slam champion Iga Swiatek in the United Cup semi-finals.
Gauff helped lift the US into the final four with a singles and doubles win in Wednesday's quarter-final against Greece in Perth.
The two-time major winner beat Maria Sakkari 6-3 6-2 before teaming up with Christian Harrison for a thrilling 4-6 6-4 [10-8] victory over Stefanos Tsitsipas and Maria Sakkari, decided on a tense match tiebreak.
The defending champion US team will next face the winners of Friday's quarter-final showdown between Poland and Australia in Sydney.
Australia's top-ranked female is world No.32 Joint, but Poland look to have the stronger hand as they're headlined by world No.2 Swiatek, who hammered the teenager in their only meeting in Seoul last September.
Gauff trails Swiatek 11-4 in their head-to-head battle, even though she's won their past three matches. The American, though, has yet to play 19-year-old Joint.
Swiatek beat Eva Lys and Suzan Lamens during the group stages of the United Cup, and would again shape as a formidable opponent for Gauff if they meet in the semi-finals.
"Obviously we've played each other a lot of times. Last year, I had a good match against her," Gauff said, talking of her 6-1 6-1 win in the semi-finals of the Madrid Open.
"I'm looking forward to the battle. I feel like when I'm playing great tennis, it puts a lot of pressure on them.
"And Maya, I've never played her, but obviously a great talent, can play really well, ball strike can be really clean.
"Either way, I'll have my hands full, but I'm just excited to go to Sydney and hopefully play some good tennis."
If Joint can pull off a huge upset against Swiatek it would go a long way towards Australia reaching the semi-finals, but in that Korea Open defeat, the youngster won only two games.
Australia's world No.6 Alex de Minaur will also face a tough examination from a former top-six player Hubert Hurkacz in the men's singles rubber.
Hurkacz has slipped to 83rd in the world after missing the second half of last year due to knee surgery.
But the 28-year-old Pole has posted two impressive singles wins at the United Cup, including a 6-3 6-4 triumph over world No.3 Alexander Zverev.
In Thursday's action in Sydney, Belgium face off against Czechia for a place in the semi-finals.
Belgium's Zizou Bergs is set to face Jakub Mensik, while world No.5 Elise Mertens is up against two-time grand slam champion Barbora Krejcikova.
