Canadian teenager Denis Shapovalov made some big plays, but plenty of mistakes too, and in the end was no match for the class or power of Juan Martin del Potro.
The match of the day didn't quite live up to the hype. Shapovalov was probablyguilty of trying a tad too hard, pushing for a bit much. But then again he had to.
Shapovalov, world No 50, had beaten del Potro, the 2009 US Open champion, once before en route to the Canadian Open final but not like this.
The 18-year struggled to get going – 57 percent on first service while del Potro went at 71 per cent.
At other times Shapovalov looked the goods successfully charging to the net with such comfort; picking the ball up off his feet, covering the court with speed and varying his game with drop shots.
The crowd appreciated the underdog's talent and energy.
And, still, del Potro did it with ease. When his big forehand connected cross court or down the line it was near unstoppable.
Eleven years Shapovalov's senior, he showed his experience and poise. Del Potro needed just 24 minutes to take the first set, and the match was done 6-2 6-4 in 65 minutes.
No doubt Shapovalov is one for the future. He will learn plenty from this defeat.
But this was del Potro in cruise mode. Russia's Karen Khachanov, next up in the quarterfinals, should be worried.
Two time champion John Isner knocked out
The final match last night was one of the best contests of the tournament, with Hyeon Chung upsetting fourth seed John Isner 7-6 (3) 5-7 6-2.
The match, which stretched on for almost two and a half hours kept the large crowd completely absorbed, with hardly anyone leaving even as the arena clock ticked well past 11 p.m.
For long periods Chung managed what is usually a near impossible feat — he neutralised Isner's booming serve.
World No 62 Chung returned exceptionally, reading the Isner serve, and constantly moved the 2.08m American around the court.
Isner still served 30 aces, but Chung's attract to get the ball back in court meant the world No 16 was often under pressure.
Chung was a deserved winner of the tie break and also forced the issue for much of the second set.
But Isner saved three break points, before converting one on the Chung serve.
But the Korean was peerless in the final set, breaking Isner twice to record his first vicotry over the former world No9.
Sock crashes out, denies tanking
Defending champion Jack Sock has been dumped out of the ASB Classic in straight sets, but denied that he was disinterested.
The American world No 8 proved a major disappointment, succumbing meekly 6-3 6-3 in 62 minutes to unheralded German Peter Gojowczyk.
Sock struggled from the outset, losing the first set in 29 minutes, and after being broken in the seventh game of the second completely lost his temperament. His head sunk and he attempted unnecessary shots between his legs.
He gave the distinct look of wanting to be anywhere but Auckland centre court.
"I was trying the whole match," said Sock after the match.
"Am I the first top 10 guy to lose to a guy outside the top 50? Probably not. It was my first match of the year I don't know what you guys really expect of me."
This was Sock's third loss in 11 matches in Auckland, having previously made the final and last eight to go with his title last year.
But after also losing his opening round doubles match Sock won't be hanging around any longer this year.
The victory over Sock was just the second over a top 10 player for Gojowczyk. He will now meet Dutch veteran Robin Haase, who took care of Lukas Lacko 7-6 (4) 6-3, in the quarterfinals.
Vesely is a former champion here - having taken the 2015 title - but was the underdog against the world No13 Querrey, who is coming off a career best year.
But he was better on the big points and held his nerve, despite Querrey firing down 24 aces across the course of the match.
Roberto Bautista Agut progresses
Spanish fifth seed Roberto Bautista Agut survived a sluggish start to oust American Steve Johnson in the opening match on Wednesday.
Spain's Roberto Bautista-Agut takes centre court today at the ASB Classic. Photo / AP
Bautista Agut, who downed Kiwi Michael Venus in straight sets in his opening match and had beaten Johnson in their four previous clashes, looked in strife after dropping the first set in 35 minutes but recovered swiftly to progress to the last eight with a 2-6 6-2 6-1 victory.
Bautista Agut will meet the winner of third seeded American Sam Querrey and Jiri Vesely in the quarterfinals.
"I didn't expect the beginning of the match," admitted Bautista Agut. "He was playing some unbelievable shots, some really good points in the first set. After the first set I said to [myself] I had to change something."
"[From there] I went more for the return…I played very good returns and I went to the net more on the return. I started to play with more first serves and everything changed."
