Four singles competitors, four former Top 5 stars — and each of them will be eager to break back into that elite group in 2024.

Friday’s marquee United Cup quarter-final will pit second seeds Greece, led by Stefanos Tsitsipas and Maria Sakkari, against the 16th-seeded Germans, whose hopes rest on Alexander Zverev and Anqelique Kerber. Both teams snuck out of their Sydney groups into the knockout rounds with 1-1 records: Greece topped Group B while Germany’s effort was enough to progress despite a second-place finish in Group D.

Both Tsitsipas and Zverev ended the 2023 season at the Nitto ATP Finals, though neither advanced to the semi-finals in Turin. Just before the season finale, they contested their 13th Lexus ATP Head2Head matchup, with Tsitsipas winning at the Rolex Paris Masters to improve to 9-4 in the rivalry.

The Greek, a 7-6(2), 6-4 winner on that occasion, is expecting another hard-fought battle at the United Cup.

While Tsitsipas has played just one singles match (and one doubles match) so far this season — including a 6-2, 6-3 singles cruise against Canada’s Steven Diez — Zverev has already taken the court four times. In two singles matches, Zverev notched a pair of three-set wins against Lorenzo Sonego and Adrina Mannarino. He also split two doubles outings, both alongside Kerber.

Germany’s Kerber — the lone former Grand Slam champion among the teams — will be seeking her first singles win of 2024 when she meets Sakkari for the fifth time. The three-time major singles titlist is 3-1 against the Greek, though the pair has not met since splitting two 2021 meetings.

Sakkari, despite a perfect 2-0 singles record in the United Cup group stage (d. Seguel, Fernandez) is wary of her veteran opponent.

The winner of this quarter-final tie will meet ho