Off-field earnings for star players often dwarf the on-field rewards of their sport, but Federer arrived at the O2 Arena having amassed an incredible $109,853,682 in prize money nonetheless.
He then added $382,000 for the Sock and Alexander Zverev wins, and $105,000 from a participation fee, which the ATP confirmed is counted as prize money.
That brought Federer's total to $110,340,682, while Tiger, after controversy and injury sparked a slide he may never fully recover from, has won a "mere" $110,061,012 on the PGA Tour. However, Woods' overall prize pot is boosted to the tune of another several million dollars by money won in non-PGA Tour events.
The next highest earning tennis player is Novak Djokovic, whose career winnings total $109,805,403. Rafael Nadal is a relative poor relation after that, not yet reaching nine figures; the last Big Four member, Andy Murray, is fourth among them, with career prize money just shy of $61 million.
If Federer triumphs in the semifinals, he will earn an additional $585,000, and the final bounty is $1.2 million -- with a bonus for any player who can go undefeated through the tournament.
A lot of players and pundits have been pointing out this week that is a long, hard season at the top of tennis. It's a pretty lucrative one, too.
Will Uncle Toni stay on Rafa's team?
Amid all the hullaballoo surrounding Nadal's withdrawal from the finals through injury, the departure of coach Toni Nadal from the world No. 1's team passed by almost unacknowledged.
The Spaniard's painful defeat to David Goffin on Monday signalled the end of his season, and the point at which his uncle planned to step down and concentrate on academy work.
There has been a fair amount of debate at the O2 Arena about the chances of 56-year-old Toni actually staying on the sidelines of his nephew's career, particularly with Rafael Nadal nursing a knee injury.
Before leaving London, Nadal told reporters that his team's experience in managing tendinitis problems he had in the past was grounds for optimism about his recovery. However, his mentor of 28 years has surely been a key part of that.
Uncle Toni, who was grumbling obliquely about the "clever" ATP before Nadal's withdrawal, may find it tough leaving all the key decisions to Rafa and new coach Carlos Moya.
Sock is game for a laugh
If there was a prize for the player who had the most fun at the ATP Finals, it would surely go to Jack Sock.
The American has been full of fun and produced flashes of brilliance, as well as working really hard.
In beating Marin Cilic Tuesday, he engaged with the crowd, encouraging them to cheer, shared a joke with the umpire and lobbed a few balls to fans.
He made Federer laugh after their match Sunday, too, after turning his back and expecting the Swiss to hit the ball at his backside.
Even when he is not competing, Sock still appears to be making the most of his unexpected appearance here, having only qualified earlier this month from the final event, the Paris Masters.
Goffin late to the Belgian team party
Goffin produced some punchy shots in dismissing the injured Nadal in a gruelling encounter on Monday, but he may have to work on a different style of combinations after he has left the finals.
The Belgian will join up with his country's Davis Cup team when he departs from London as they prepare for their final against France in Lille next week (Nov. 24-26).
They have been spending some time off the court this week, perhaps with their neighbours and rivals in mind, and Goffin may have to play catch-up.
This article has been updated to correct the statistic regarding Tiger Woods' career prize money, which incorrectly stated his PGA Tour earnings as the overall prize money won in his career to date.