Roger Federer has won the ATP Finals six times in his career. (Getty Images)

Each week, Baseline will take a look at a player who has thrived at one of the stops on the ATP and WTA tours during their career.

2016 marked a significant chapter in the history of the ATP Finals: It was the first time since 2001 that Roger Federer didn’t play in the season-ending championships. He returned to the field the next three years, but has missed this edition due to injury.

That’s two absences in a nearly two-decade span, a nearly unheard of level of consistency in the sport. And he’s made the most of his time wherever the tournament has been held, claiming six titles to become the winningest champion at the event for the game’s best players.

Making his debut at the tournament in 2002, when it was held in Shanghai, the 21-year-old world No. 6 stormed through round-robin play to set up a semifinal against defending champion Lleyton Hewitt. The top seed then beat his budding rival in three hard-fought sets.

When Federer returned to the tournament the following year—this time, held in Houston, Texas—he was at a different place in his career as the reigning Wimbledon champion. His campaign at the year-end tournament got off to a solid start with an epic win against Andre Agassi in his opener. The two met again in the final, and this time, it was a more straightforward victory as Federer beat the American in straight sets to win his first trophy at the season finale.

Another victory followed the next year, when he beat Hewitt in the final. Extending his winning streak at the tournament to 14 matches in 2005, Federer couldn’t extend it to 15, as his rival from the juniors, David Nalbandian, rallied from two sets down to win in five. That loss also kept Federer from breaking John McEnroe’s single-season winning percentage mark set back in 1984.

As he kept winning around the world and dominating the men’s game, it was only fitting that his reign would continue from start to finish over the season: Between the 2006 and ’07 tournaments, he only dropped one round-robin match at the year-end event, topping James Blake and David Ferrer in those respective finals.

In 2008, the ATP's year-end event was held for the last time in China. However, Federer didn’t go out on a high note there as he failed to make out of round-robin play for the first time in his career. When the tournament moved to London for 2009, he was stopped in the semifinals by Nikolay Davydenko.

Seemingly determined to make up for that defeat the following year, Federer didn’t drop a set through his round-robin matches and the semifinals. Having lost the top spot in the rankings to Rafael Nadal, Federer stopped the Spaniard in the final to win the title for the fifth time.

And as Novak Djokovic was running away from the rest of the field in 2011, it was Federer who was the last man standing as he beat Jo-Wilfried Tsonga in the London final.

Federer was again denied a three-peat when Djokovic won the 2012 title. Then, he lost to Nadal for the first time at the tournament in 2013, ending his run in the semifinals. Federer advanced to the final the next two years against Djokovic, experiencing defeat under different circumstances: He was unable to play the championship match in 2014 due to injury and then lost in straight sets to the Serb in ’15.

After missing the 2016 tournament because of an injury-shortened season, Federer reached the semifinals in his return to cap off a resurgent year that saw him win two Grand Slam titles. Two of the sport’s brightest young talents, Alexander Zverev and Stefanos Tsitsipas, stopped him at that stage in 2018 and ’19, respectively, on their way to their first triumphs at the tournament.

Federer was in contention to make another appearance this year among the world’s top eight players, but an injury shortened his 2020 campaign. Planning to return to action next year, it would be hard to count him out as he attempts to qualify again at 40, and achieve more milestones in his legendary career.