Stefanos Tsitsipas got the better of Alexei Popyrin to tighten his grip on top spot in the Ultimate Tennis Showdown after the third weekend of the series.

Greek rising star Tsitsipas came from behind to sneak a 3-2 success over Spanish veteran Feliciano Lopez on Saturday, and he followed that on Sunday with a 3-1 triumph against Australian prospect Popyrin.

The behind-closed-doors and unorthodox tournament is being staged across five consecutive weekends at the Cote d'Azur tennis academy run by Serena Williams' coach Patrick Mouratoglou, with a quickfire format aimed at attracting new fans to the sport.

Each match consists of four 10-minute quarters, rather than sets, with a point going to the winner of each quarter.

A sudden-death tie-break follows at the end of the match if scores are level at two quarters each, with the first player to take back-to-back points declared the winner.

World number six Tsitsipas has now won five of his six matches in the competition, putting him ahead of Italian Matteo Berrettini and France's Richard Gasquet, who each have won four times but lost twice.

Dominic Thiem, who has played just four matches, has won three times and lost once, and this weekend the Austrian world number three earned 3-1 successes over David Goffin and Berrettini.

Gasquet suffered a 4-0 loss to Berrettini on Saturday but bounced back by beating fellow Frenchman Corentin Moutet 3-1 on Sunday.