LONDON -- Jack Sock won't lack support when he makes his debut at the ATP World Tour Finals. His father and brother are flying in from the United States, and they'll be joined by Sock's girlfriend at London's O2 for the season-ending event, which begins Sunday.
But the support Sock should be most thankful for comes from the people he is much closer to -- literally -- on the tennis court. His doubles partners.
Sock's path to the top of the game came much differently from that of the other players in the field. He is the only one of the eight competitors in London who has won Grand Slam doubles titles. It began more than six years ago when Sock partnered with American Melanie Oudin to win the mixed-doubles championship at the 2011 US Open. Three years later, Sock joined forces with Canada's Vasek Pospisil to capture the men's doubles crown at Wimbledon.
"I think any success you can have on the tennis court, doubles helps," Sock told ESPN.com. "If you're playing on the weekend, you're in the trophy ceremony at the end of it, one of the last guys in the locker room, it can only give you confidence."
The 25-year-old has reached the ATP Finals for the first time, thanks to a superb late push. He won the Paris Masters, a 1000-level event, last weekend, a feat that earned him enough points to join the elite field.
Sock has played 13 doubles events this year, with a number of different partners, and he played the doubles competition for the Unites States in two Davis Cup ties this season.
"I thoroughly enjoy doubles, everyone knows that," Sock said. "It does give you confidence. You can work on a lot of things that can correlate to your singles game. I enjoy getting out there."
When he was trailing Britain's Kyle Edmund 5-1 in the final set of their first-round match in Paris last week, qualifying for London was the last thing on Sock's mind. But as a few points went his way, he battled his way through to his first Masters title, which was a massive confidence boost as he prepares to face the world's best over the next week.
Sock won't be able to ease himself into the draw, though. He will play Roger Federer, the 19-time Grand Slam winner, in the opening match of the tournament. How's that for a stern introduction to the ATP Finals? The pair have met three times in the past, with Federer winning all three.
And let's not forget Federer is coming to London off one of the strongest campaigns of his career. He won the Australian Open in January and took home his eighth Wimbledon trophy this summer. In all, Fed owns seven titles in 2017.
At the launch party inside the Tower of London on Thursday, Sock, the first American to qualify since 2011, said he was "playing with house money" after making it into the draw at the last minute. But that doesn't mean he's not thinking about pulling off the upset.
"Any time you can play the greatest of all time is a fun experience," he said of the Federer match. "I've played him a few times. At first, I don't think there's too much belief that you can get by him, but I think now, playing him a few times, I'll talk with my coaches and my team and figure out the best game plan for me and go out there and try to execute."
Always a confident player, Sock was given a public talking-to during the Laver Cup, when his team captain, John McEnroe, told him in no uncertain terms that he belongs at this level and that he needed to show the best players he was not intimidated by their presence.
"I've always had belief in myself, but to have it come from such a legend like that was special," Sock said. "It was a cool event, the Laver Cup. It was special for every player there. Every time Johnny Mac would say something, everybody would listen intently. I think it's a nice reminder. I do always have the belief in myself, but it's nice to hear from a guy like Johnny Mac."
Was the pep talk enough to get him by Federer? If ever there was a time, Sunday looks as if it could be that moment.