Andy Murray will play his first competitive match on home soil since becoming the US Open champion when he faces Tomas Berdych at the ATP World Tour Finals on Monday.
The Scot, who ended Britain's 76-year wait for a male Grand Slam singles champion, meets Berdych at 13:45 GMT.
It will be the opening round-robin singles match of the season-ending championships at London's O2 Arena.
Novak Djokovic, back at world number one, plays Jo-Wilfried Tsonga at 19:45.
It was Djokovic whom Murray beat to win his first Grand Slam title in September, and the 25-year-old from Dunblane can expect vociferous support from the 17,000 spectators when he takes to the court.
"I'll have to wait and see what it's like when it does happen but obviously it will be nice," he said.
"I'm sure all the players will say it's one of the nicest arenas to play in, the atmosphere's great and it's packed from the beginning - from the first point of the matches right through to the end, which isn't always the case."
Roger Federer, David Ferrer, Juan Martin del Potro and Janko Tipsarevic have been drawn in Group B, which begins on Tuesday, with the top two players from each group progressing to Sunday's semi-finals.
Murray has a losing record against Berdych, the Czech having won four of their seven matches, but the Scot prevailed over four sets in the US Open semi-finals in September.
"It's probably one of the hardest matches to start," said Berdych.
"It's kind of revenge for the US Open but it's another match. Of course the crowd's going to be on his side, but what I like about this crowd is that they're one of the best tennis crowds I ever played in front of, so I think it's going to be just fine."
Murray has yet to make it past the semi-finals at the O2 but expectations have never been higher in a year that has seen him break his Grand Slam duck and win Olympic gold.
"There's always pressure at all of the major tournaments," he said.
"I feel a little bit more relaxed coming in this year than I have done in previous years because I managed to win the US Open, but there's going to be pressure on me here to play well.
"The only thing I can guarantee is that I'll give 110% on the court, fight as hard as I can to the end of all of the matches and see where that gets me. Hopefully it will get me a few wins."
Murray has reunited with coach Ivan Lendl in London for the first time at a tournament since his US Open win after the Czech arrived in London on Friday.
The pair began making plans for the round-robin matches on Sunday.
"I knew my first match was going to be against either Berdych or Del Potro," said Murray.
"There are obviously differences in their games but they're both big guys, big hitters, flat hitters of the ball, and can generate power and winning shots from all parts of the court, so you need to try to use some variety.
"Against all of the guys here you're going to have to play a top-quality match to win.
"You're going to have to make slight adjustments to your tactics in all of the matches. I'll go through the tactics for that match with Ivan on Sunday."
Djokovic and Murray are the form players at the very top of the game right now, something that six-time season-ending champion Federer acknowledged.
"It motivates me, it doesn't annoy me," said the Swiss, "because they deserve the limelight as well. It's great that we have a lot of champions out there right now playing the game.
"I was very happy for Andy that he made his move at the Olympics and also at the US Open. It was always going to be natural that he was going to get more limelight, and Djokovic after his incredible year last year was always going to have the limelight on his as well.
"Right now it seems like they're in their prime and this is when they are supposed to play their best tennis."
Britain is also represented in the doubles at the O2, where Jonny Marray and Dane Freddie Nielsen qualified on the back of their stunning Wimbledon triumph in July.
They will get their Group B campaign under way on Tuesday against India's Mahesh Bhupathi and Rohan Bopanna.