But it was a pair of errors from Zverev in the final game that gave Sock the match.
"Nobody put a gun to my head to come and play", Nadal said about his decision to participate in the ATP Finals in London.
But, of course, it would be naïve to write off the fiery young German too early. It happened most recently in 2016 when he struggled with a wrist injury. According to reports, Detroit Red Wings right wing Luke Witkowski was suspended 10 games by the NHL for leaving the bench and returning to the ice during a brawl with the Calgary Flames Wednesday night. It's hard, but at the same time it's part of our daily life.
That's one reason why the world No. 2 insists chasing the world No. 1 ranking will not be his primary pursuit next season.
Dimitrov also made it back to the last four at a Grand Slam, pushing Rafael Nadal to five sets before losing a classic encounter at the Australian Open.
It could have gone either way, even the last rally of the match was a fraught, drop shot fuelled fight.
Moments later, it was the 20-year-old who found himself facing three break points but some big serving allowed him to hold on.
'That was a roller-coaster match for sure, ' said Sock. Sometimes you have to let your frustration out and it worked I guess. The only misfire at 19-times winner of Helmets occurred in 2008, when the Swiss lost to Andy Murray and Gilles Simon. And again 'come on Roger!' on set point to Cilic.
The American had the advantage in the shortest points, managing to tame Zverev's lethal first groundstroke after the serve, and he also stole the show in the longest points, leaving Sascha to dominate in the mid-range segment, which proved not to be enough.
The American caused the heavily fancied world No. 3 all sorts of problems with his backhand slice, powerful serve and forehand, and his general unpredictable trickery to join Roger Federer in escaping Group Boris Becker.
Roger Federer speaks! 'It was a tough match.