Roger Federer made a strong start to his bid to cap his golden year with a seventh ATP Tour Finals title as the Swiss star defeated Jack Sock 6-4, 7-6 (7/4) on Sunday. Four months after winning Wimbledon for a record eighth time just a few miles across London, Federer is back in the English capital aiming to cap a remarkably successful spell by lifting the silverware at the O2 Arena. When Federer missed last year's Tour Finals through injury, it seemed possible he would never recapture his former glories.
He came into 2017 having missed half of last season due to fitness problems and was without a Grand Slam title since 2012.
But the 36-year-old has enjoyed a stunning renaissance, winning the Australian Open and Wimbledon among seven titles -- more than other male player over the last 11 months.
Federer hasn't triumphed at the season-ending Tour Finals since 2011.
But after seeing off Sock in his group opener, the world number two has now won his last 11 matches.
That dominant streak has already earned him titles in Shanghai and Basel, and he hopes to maintain that hot streak all the way to the Tour Finals crown next weekend.
With defending champion Andy Murray, Novak Djokovic and Stan Wawrinka all absent from the Tour Finals due to injury, Federer and Rafael Nadal are the unquestioned headline acts.
Having won the French and US Opens this year, Nadal has matched Federer's unexpectedly dominant run as the old rivals hoovered up all four of this year's Grand Slam crowns.
Nadal is already guaranteed to finish as the year-end world number one for the first time since 2013, making the 31-year-old the oldest man to earn that honour.
But Nadal's hopes of finally winning the Tour Finals for the first time could be hampered by injury.
Nadal, twice a Tour Finals runner-up, is due to open his campaign against David Goffin on Monday, however the Spaniard admits he is still struggling with the knee problem that forced him to pull out of the recent Paris Masters.
Caught off guard
While Nadal fretted over his fitness, Federer was back in the groove against Sock, who had grabbed the last Tour Finals berth by winning his first Masters title in Paris earlier this month.
Even the 25-year-old, yet to make it past the last 16 at any Grand Slam, was caught off guard by his climb to a career-high ninth in the rankings.
He was forced to cancel a scheduled round of golf at Augusta as he instead prepared to face Federer.
A relaxing stroll around that famous course might have seem preferable to facing Federer, who hadn't lost a set in their three previous meetings and quickly took charge with a break in the first game.
That was all the advantage Federer needed as the 19-time Grand Slam champion swept through the first set with 10 winners and four aces.
Federer didn't have it so easy as Sock found some rhythm in the second set, but the Swiss held his nerve to take it in a tie-break.
Fans hoping for some young blood to challenge Federer and Nadal will get a glimpse of a potential future star when Germany's Alexander Zverev makes his tournament debut against Croatia's Marin Cilic later on Sunday.
Zverev is the youngest Tour Finals qualifier since Juan Martin del Potro in 2008, the towering 6ft 6in 20-year-old having underlined his emergence with five titles this year.