Image source, Getty Images
Luke Littler became the youngest world darts champion, aged 17, in January
Frank Keogh
BBC Sport Senior Journalist
Luke Littler is chasing a third consecutive title but was made to work for his place in the New Zealand Masters quarter-finals.
The world champion, who has just won the World Matchplay and Australian Masters in succession, was far from his best in beating Kiwi Mark Cleaver 6-4 to reach the last eight in Auckland.
England's Littler, 18, won the first three legs but was pegged back at 4-4 after some sloppy darts before recovering to clinch victory.
The teenager, who averaged 95.60 and did not hit a 180, faces World Grand Prix champion Mike De Decker on Saturday in a rematch of last week's final in Australia.
Luke Humphries began his defence of the New Zealand title - the second leg of the World Series of Darts Oceanic double-header - with a 6-3 win over Haupai Puha.
But Humphries admitted he is not happy with how he is playing after also failing to score a maximum and averaging just 89.47.
"I'm out of sorts and out of form. I don't think I've had one good game in two months," said the Englishman, who won the Premier League at the end of May.
"I know I can bounce back. It's one of those things you go through in sport."
The world number one beat Damon Heta in the final to triumph last year and they will face each other again after the Aussie thrashed Dean Hyland 6-1.
Top seed Stephen Bunting, aiming to add to his victories at the Bahrain Darts Masters and Nordic Darts Masters earlier this year, progressed past Ben Robb 6-3.
Welshman Gerwyn Price missed double 12 for a nine-darter and averaged more than 103 as he edged out Jonny Tata 6-4 to set up a quarter-final against Northern Ireland's Josh Rock.
New Zealand Masters first round results
Mike De Decker 6-1 Gordon Mathers
Josh Rock 6-2 John Hurring
Gerwyn Price 6-4 Jonny Tata
Damon Heta 6-1 Dean Reyland
Stephen Bunting 6-3 Ben Robb
Luke Humphries 6-3 Haupai Puha
Luke Littler 6-4 Mark Cleaver
Chris Dobey v Simon Whitlock
Saturday's schedule
19:00 local time, 08:00 BST
Quarter-finals
Best of 11 legs
Stephen Bunting v Chris Dobey/Simon Whitlock
Luke Humphries v Damon Heta
Gerwyn Price v Josh Rock
Luke Littler v Mike De Decker
Semi-finals
Best of 13 legs
Final
Best of 15 legs