(Reuters) - Alexander Bublik tried everything to unsettle Jannik Sinner at the Miami Open on Wednesday but with the Italian teenager keeping his composure to win 7-6(5) 6-4 the Kazakh was left convinced he had been beaten by a robot.
Bublik used underarm serves, drop shots and a sneak-attack serve return against Sinner during the quarter-final of the ATP Masters 1000 event but fell to his second straight defeat to the 19-year-old following a loss in Dubai in mid-March.
"You are not a human," Bublik told Sinner at the net after the Italian had wrapped up the match. "You are 15-years-old and you play like this. Good job."
2019 Next Gen ATP Finals winner Sinner has made rapid progress over the last two years, reaching his maiden Grand Slam quarter-final at last year's French Open and now sits at a career-high 31st in the world.
In February he became the youngest player since Novak Djokovic in 2006 to win two ATP titles by claiming the Great Ocean Road Open after his Sofia Open title at the end of 2020.
"He's not (human). That's a fact," world No.44 Bublik later told reporters. "For me it's very surprising that the guy at his age has this mental toughness that many, many other players don't have.
"I called him a robot couple of times during the match, but I do it in a very sincere way because he's really, really a great player."
Sinner had to be focused against Bublik, who has already reached two finals this season.
Rallying from a break down in each set, the Italian was not only on the receiving end of a sneak-attack return and the underarm serves but also watched on helplessly as Bublik hit a 105mph forehand return against his serve.
The Kazakh was also impressed with the shot and asked the chair umpire for the speed of his rocket return, adding that it was "the best forehand I've ever hit in my life".
(Reporting by Sudipto Ganguly in Mumbai; Editing by Peter Rutherford)