Alexander Zverev has beaten Rafael Nadal in their opening round-robin match of the ATP Finals.
The loss dents Nadal's chances of ending the year as the number one ranked tennis player in the world.
He entered the season-finale in London with an abdominal injury.
Tuesday's match sees Roger Federer, who also lost his opening encounter, take on Italy's Matteo Berrettini.
Play gets underway at 6:00 pm UAE time.
PSG retain Champions League title with shoot-out win over Arsenal
Paris St Germain held their nerve in a cagey Champions League final to retain the title by beating Arsenal 4-3 on penalties as Saturday’s showdown ended 1-1 after extra time, cementing the French side's status among Europe's modern greats.
French Open champion Gauff knocked out by Potapova in third round
Defending French Open champion Coco Gauff has been knocked out of the Grand Slam following a 4-6 7-6(1) 6-4 loss to Anastasia Potapova in the third round at Roland Garros on Saturday.
Sabalenka sees off Kasatkina to reach French Open fourth round
Aryna Sabalenka has cut through the French Open chaos as the world number one beat Australia's Daria Kasatkina 6-0 7-5 on Saturday to seal her place in the fourth round after seismic upsets in the previous two days at Roland Garros.
Parry stuns Anisimova to reach first Grand Slam fourth round at French Open
Diane Parry, the last Frenchwoman standing in the French Open women's draw, has pulled off a stunning 6-3 4-6 7-6(3) victory over American Amanda Anisimova on Saturday, advancing to the fourth round of a Grand Slam for the first time in her career.
Osaka survives three-set scare against teenager Jovic
Naomi Osaka has dazzled with an all-gold outfit but had to dig deep for a hard-fought 7-6(5) 6-7(3) 6-4 victory over American teenager Iva Jovic on Saturday to reach her first-ever French Open fourth round.
Risk It All
Bruno Mars
Can't Stop The Feeling
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Beautiful People
Ed Sheeran & Khalid
