Federer, the current world No 2 in tennis, qualified for the semi-finals of the year-end ATP Finals in London on Tuesday night with a 7-6, (8/6), 5-7, 6-1 victory over German world No 3 Alexander Zverev. But, the Nebraska man showed brilliant persistence and athleticism to reach the ball that needed a full stretch and sliced the dropping ball with a backhand slice with impeccable pace and placement. "What I like to see is I feel like he's working towards how he could be playing when he's 23, 24 in terms of his fitness, planning, organisation, all these things".
When they played in fast conditions at Wimbledon, Federer strolled to victory and the likelihood is he'll do so again. The belief in himself is great. "I still have a very decent chance of being in the semi-finals". Thiem and Goffin will square off in a do-or-die contest on Friday.
"I'm excited for Alex's future".
But a few options were becoming clearer, particularly as Roger Federer, top seed in the Boris Becker Group, was the only one of the four to win his opener in straight sets.
Zverev looks a worthy favourite though.
Nineteen-time Grand Slam champion Roger Federer has overtaken former world number one golfer Tiger Woods as the highest prize money earner in individual sports, according to a list released by Forbes.
Federer, who has won 95 tournaments through his ATP career that began in 1998, can bank more cash should he continue to progress in the ATP World Tour Finals.
He raised more $4m (£3m) earlier this year playing exhibition matches in Switzerland and the USA.
Sock: "I'm just focused on my tennis".
The head-to-head between these two is knotted up at one apiece.
Zverev might rue missed opportunities, having squandered a set point and 4-0 tie-break lead in the first set, but it was concentration and stamina that ultimately proved the difference. It literally sounded like the intercom I thought was in our room.
It means the 36-year-old is certain to move into this tournament's semi-finals, even before his final group match against Marin Cilic, while Zverev faces American Jack Sock for the second qualifying spot. Although Cilic had a slender 15-14 record in shootouts this year, dwarfed by his opponent's cucumber-cool 21-8 margin, he wrapped up the set from 6-5 on his serve with a clean forehand winner. I guess from what the workers at the hotel said, the location of your room is how loud the alarm is.
Federer continued: "I'm talking to myself, saying, 'What am I even getting upset about?" "He's the best player of all time", Zverev said. "Then I realized it was four a.m., so I hoped it wasn't just a test from the hotel".