Coverage:Watch live coverage of one match per day on BBC TV, BBC iPlayer and online; Listen on BBC Radio 5 Live Sports Extra; Live text on selected matches on the BBC Sport website and app. Clickherefor Live Guide.
Sixth seed Stefanos Tsitsipas won his opening match at the ATP Finals by edging out fourth seed and fellow debutant Daniil Medvedev
The Greek 21 – year-old beat the Russian 7-6 (7-5) 6-4 at the O2 Arena.
There was just one break of serve in the match with Tsitsipas, the youngest player in the tournament, earning his first win over Medvedev – a player with whom he has a **** rivalry.
“It is one of the toughest and most important victories,” Tsitsipas said.
“It’s not easy coming in knowing you’ve lost five times before [to Medvedev] but this victory means a lot to me, this crowd means a lot to me.
“” [There are] Greek flags everywhere – it almost feels like I’m playing i n Athens. “
World number one Rafael Nadal plays defending champion Alexander Zverev later on Monday in the same group.
Novak Djokovic, who can overtake Nadal at the top of the world rankings this week, leads the other group after winning on Sunday.
The top two players in each group after the round-robin stage progress to the semi-finals on Saturday.
The men’s season-ending event, which is taking place in London for the penultimate year, features the top eight players of the year.
‘We won’t go for dinner together’ – Tsitsipas on Medvedev rivalry
Image copyright Getty Images Adults in England without an A-level or equivalent qualification will be offered a fully funded college course, the government has announced.The offer will be available from April and applies to courses offering "skills valued by employers".In a speech on Tuesday, the PM will say the government cannot "save every job" amid…