Argentinian star Juan Martin del Potro has passed his first Auckland Classic examination, unleashing a brutal ground-stroke game to defeat Canadian young gun Denis Shapovalov 6-2 6-4.
Cutting a slightly lumbering figure, del Potro was nevertheless highly effective in the second-round clash against his prodigious opponent, who made too many unforced errors.
The 29-year-old del Potro, the No.2 seed, thrashed eight aces and flummoxed Shapovalov with a number of vicious forehands, cruising to a 65-minute victory on Wednesday.
With top seed Jack Sock eliminated earlier in the day by unheralded German Peter Gojowczyk, del Potro is a red-hot favourite to lift his first Classic title since 2009.
He'll face another up-and-comer in the quarter-finals in Russian Karen Khachanov, who defeated Uruguayan sixth seed Pablo Cuevas earlier in the afternoon.
Sock's exit was the story of the day in Auckland.
Gojowczyk, ranked 65th in the world, tipped over the American 6-3 6-3 and dominated from first to last.
Sock earned a bye to the second round due to his seeding, but looked well off his world No.8 ranking and last year's ATP World Tour Masters-winning form.
He made unforced error after unforced error against Gojowczyk, who served the house down with nine aces and won 88 per cent of first-serve points.
"Up a break in the first and the guy hit some unbelievable turns, painting lines all over the place, slapping balls, coming in," Sock told reporters.
"I didn't have my best serving day which didn't help, got some free points but not as many as I'd like. It's a rusty first match. You've got to get the cobwebs off."
In further bad news for Classic organisers, American third seed Sam Querrey also dropped out at the first hurdle, losing a three-set thriller to Czech Jiri Vesely, the 2015 Classic champion, 4-6 7-6 (12-10) 7-6 (7-5).
But two other seeds, Spaniards Roberto Bautista Agut and David Ferrer, progressed without trouble against American Steve Johnson and Portugal's Joao Sousa respectively.
