Jack Sock upsets world No 3. Zverev
weeks, hang in there and keep fighting,” said Sock, who seemed to be imploding when he received a penalty point at the start of the third set.
The American mixes eye-watering power with a deft touch and it was that combination that disrupted Zverev’s game.
Sock broke for a 4-3 lead in the first set and then almost gifted it straight back but recovered from 0-40 with five unanswered points to lead 5-3. Two games later a nonchalant drop shot gave him first blood.
Zverev roared back to take the second set in the blink of an eye although Sock carried on entertaining the crowd, as he has done all week, and at one point attempted a lob played through his legs rather than dispatch a routine forehand.
When Sock dropped serve at the start of the third he launched a ball into the upper tiers of the 02 arena.
The penalty point meant Zverev started the next game 15-0 ahead but the German lost concentration and conceded four straight points to get broken.
Zverev double-faulted to gift Sock another break for a 3-1 lead and was staring defeat in the face at 4-1 down.
He battled back but it proved in vain for the 20-year-old as a season, which earned him five titles, came to a sudden halt.
Federer had already booked a semi-final spot with his earlier win over Zverev but any notion that he would coast through his final group match proved wide of the mark.
Cilic was hoping to end his year on a high in the city where his Wimbledon dream was ended in this year’s final by Federer with the Croatian sobbing on court after suffering blisters.
The world No 5 put up much more resistance this time, winning the first set, and when Federer served at 4-4, 30-30 in the second it seemed Cilic might enjoy some redemption.
But the Swiss simply hates to lose and when Cilic netted a forehand he pounced to square the match.
A 100mph forehand service return gave Federer an early break in the decider and he turned on the style to race to victory.
Federer has reached the last four in 14 out of 15 appearances in the year-end tournament and will face David Goffin or Dominic Thiem for a place in the final. THE INDEPENDENT