LONDON • Roger Federer has paid a glowing tribute to Alexander Zverev, hailing the 20-year-old German as having the "full package" of skills and resolve to lead tennis' youthful revolution.
Zverev offered a stern challenge before finally succumbing to Federer, a man 16 years his senior, at the ATP Finals in an absorbing three-setter on Tuesday.
Federer has lost twice to Zverev on Tour, and once in the Hopman Cup, and believes the German will be a major threat to the game's elite for years to come - and perhaps to him again even as early as Sunday.
With one win and one loss at the O2 Arena, Zverev could still feature in the other half of the draw to Federer in Saturday's semi-finals should he prevail in the winner-takes-all clash with Jack Sock today.
Federer said he was impressed not only with the world No. 3's game but also his outlook.
"I like what I'm seeing in 'Sascha'," Federer told reporters after his 7-6 (8-6), 5-7, 6-1 victory.
"I see somebody who is working towards the future. He's working towards how he could be playing when he's 23, 24 in terms of his fitness, planning, organisation."
While mentioning Zverev's name alongside that of 22-year-old Nick Kyrgios and 18-year-old Canadian Denis Shapovalov as youthful players who have impressed him, Federer added: "What I like about Zverev is he's got the full package.
"He's already No. 3 in the world. He's going to leave, regardless of whether he qualifies for the semis or not, with a lot of information."
Zverev could not manage to repeat August's Canadian Open victory over an injury-hampered Federer, which stands as the 19-time Grand Slam winner's only defeat in a final in 2017 and his only loss to a fellow top-10 player all year.
"The last six months have given him everything he needs to work forward to," added Federer.
"He's only going to get stronger from here. This should be very encouraging for him and his team."
Only Federer and Rafael Nadal have won more than Zverev's five titles this season and he felt, even in defeat, that it was yet another significant step forward.
"It was a very positive match for me," said the Hamburg native.
"If I continue this level, maybe you'll see me at the weekend."
With the victory, Federer has also overtaken 14-time Major golf champion Tiger Woods as the top prize money earner in individual sports, according to Forbes.
The win gave the Swiss a total of US$110,235,682 (S$149,502,734) in career earnings so far, surpassing Woods, who has earned US$110,061,012.
The American golfer, however, has not added significantly to his earnings since revelations in 2009 about his private life and back injuries which have hampered his progress in recent years.
Federer accumulated his winnings since his ATP Tour debut in 1998. The 36-year-old returned from a six-month injury layoff this year to win Grand Slams at the Australian Open and Wimbledon.
In the Pete Sampras group, Bulgaria's Grigor Dimitrov reached the last four on his ATP Finals debut. He dispatched Belgian David Goffin 6-0, 6-2 in 27 minutes.
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