Novak Djokovic has made the ideal start in his quest to win a record-equalling sixth ATP Finals title.
The world number two easily beat Italy's Matteo Berrettini in straight sets at the O2 Arena in London.
However, things weren't as rosy for Roger Federer, who was beaten by Dominic Thiem in his tournament opener.
It's the second year in a row that the seven-time Dubai Duty Free Tennis Championships winner has lost his opening match at the ATP Finals.
Russell edges Antonelli as Mercedes set early practice pace in Japan
Formula One championship leader George Russell has edged out teammate Kimi Antonelli in a Mercedes one-two at the top of the timesheets in Friday's opening practice session for the Japanese Grand Prix.
Sabalenka sails past Rybakina to set up Miami Open final against Gauff
Defending champion Aryna Sabalenka has eased past Elena Rybakina 6-4 6-3 on Thursday to book a Miami Open final against Coco Gauff as the world number one bids to become the fifth woman to complete the 'Sunshine Double' after her title win at Indian Wells.
Croatia beat Colombia 2-1 in World Cup warm-up
Croatia has secured a 2-1 win over Colombia in a World Cup warm-up match on Thursday, overturning an early deficit with goals from Luka Vuskovic and Igor Matanovic.
Italy, Sweden and Denmark close in on World Cup spots
Italy moved within one win of ending their 12-year World Cup absence with a 2-0 qualification playoff semi-final victory over Northern Ireland on Thursday thanks to second-half goals from Sandro Tonali and Moise Kean.
Gauff crushes Muchova to reach Miami Open final
Coco Gauff delivered a commanding 6-1 6-1 demolition of Karolina Muchova on Thursday to book her place in the Miami Open final, her sixth WTA 1000 final.
