Roger Federer reached his 14th semi-final in his 15th appearance at the year-end ATP Finals by overcoming Alexander Zverev 7-6 5-7 6-1 in just his second-round robin group match.
The victory for the oldest ever competitor at the event against the youngest in nine years saw 36-year-old Federer stay on course for a record seventh title triumph at the tournament.
And with world No.1 Rafa Nadal withdrawing through knee trouble, the odds are even shorter on the Swiss master achieving his stated aim of glory under the dome at the 02 Centre in London.
I still think I have great chances of qualifying, playing Jack Sock next. If I continue at this level, maybe you’ll see me on the weekend still. The third set against Roger was upsetting but it was a pretty positive match. We both played pretty well Alexander Zverev
Federer said: “I’m extremely happy to be through in two matches in a tough group. It was difficult against Sascha (Zverev’s nickname). From beginning to the end.
“Still early days in the tournament. It was nice to be able to show that quality of mine that I can dig out these matches, these points, time and time again. Stay mentally tough. In the third I started to play better but I lost my way a bit in the second.”
He hailed the potential of Zverev, the world No.3, reckoned to be the best of the new generation.
Federer, who backhand sliced half his returns against his taller opponent, said: “I’m very excited for his (Zverev’s) future. He’s a wonderful guy and is going to be a great player.
“What I like about about Zverev is he’s got the full package. He’s already three in the world. He’s going to leave the World Tour Finals, regardless if he qualifies for the semis or not, with a lot of information.
“The last six months of the season has given him everything he needs to work forward to. He’s only going to get stronger. That should be very encouraging for him and his team.”
Zverev was left still talking up his chances of getting to the latter stages of the Finals.
He said: “I still think I have great chances of qualifying, playing Jack Sock next. If I continue at this level, maybe you’ll see me on the weekend still.
“The third set against Roger was upsetting but it was a pretty positive match. We both played pretty well.”
Federer, a 19-time Grand Slam champion, knew he would be up against it against Zverev from first-hand experience; the precociously talented 20-year-old German inflicted one of only four defeats suffered by the age-defying Swiss this year.
That came in the final of Montreal in August when Zverev claimed his second Masters crown of a breakthrough year. And when you consider the third seed secured his first in Rome in May against Novak Djokovic, you knew he would not go all of a quiver facing greatness.
The lady in the red and white of Switzerland holding up a placard in the crowd declaring ‘genius at work’ had it right. But Zverev stood toe-to-toe with the player also often described as the greatest of all-time during much of the opening set.
The 6’6” German, sporting a red bandana and floppy long hair, may have appeared gangly but he certainly did not lack co-ordination from the baseline as he gave as good as he got in a series of breath-taking rallies.
Neither player conceded any break points until Federer saw a chink of light at the end of the first-set tunnel in the 11th game. He secured two set points . The first came after Zverev appeared distracted by an errant light from an individual mobile shining from the crowd and errored.
And the second was with the sort of flashing forehand crosscourt which made BBC commentator Andrew Castle, a former top British player, describe the world No.2 as the most beautiful player there has ever been.
But Zverev hung on to force the tie-break and race to a 4-0 lead.
Unexpectedly, the wheels came off for the German as unruffled Federer, flexible, nibble and ruthless, roared back, obtained his third set point, took it and casually strolled back to his courtside seat.
And when the Swiss broke Zverev and held for a 2-0 lead in the second set it seemed the momentum was with the tournament favourite.
Zverev was cheered on by fitness trainer Jez Green, who has developed his player’s physical resilience after helping Andy Murray in the same role, and coach Juan Carlos Ferrero, the former world No.1 no doubt taken on in August for his top-level experience .
And they saw their rapidly-developing charge pull it back to 2-2 and go on to force Federer to serve to save the set at 5-4, which the Swiss duly did.
The German levelled the match after winning and taking his third set point as Federer hit a wayward forehand on his own serve.
But Federer took an iron-grip in the deciding set by twice breaking Zverev for a 4-1 lead. The first came with the help of a massive forehand which Zverev put out.
And the second when the German dumped a forehand into the net and seemingly trying to take a bite out of his racket as if implying he knew his time was up.
Zverev forced a break point in the next game, but Federer smoothed the bump in his road to victory to leave himself a game short of victory.
And the Swiss closed it as Zverev finally crumbled on his own serve, producing a double fault on match point.