France's Fils ends 'great champion' Gasquet's 956 weeks in top 100
The 19-year-old Fils cruised to a 6-3, 6-4 victory against the 37-year-old Gasquet, who had enjoyed a remarkable 956 consecutive weeks in the top 100, peaking at number seven in July 2007.
Gasquet was defending the Auckland title and points he won 12 months ago, so the first-round defeat will see him slide down from 76th in the world when new rankings are released next week.
Fils, with a booming serve that produced nine aces, broke at 2-2 in the first set and at 1-1 in the second and applauded Gasquet as he left the court.
"He's a great champion. He did an unbelievable career so I'm really happy to play on the court with him," said Fils, who reached the quarter-finals of the Hong Kong Open last week.
"But it was a nice match for my part and I'm really happy."
In other action, Canada's Denis Shapovalov looked rusty in his first match since Wimbledon last year, losing Austria's Sebastian Ofner 6-4, 6-2.
Roberto Bautista Agut was beaten by fellow Spaniard Roberto Carballes Baena 6-4, 6-4 and eighth seed Max Purcell of Australia overcame New Zealand's 716th-ranked wildcard Kiranpal Pannu 6-4, 6-4.
The top four seeds, Ben Shelton, Cameron Norrie, Francisco Cerundolo and Felix Auger-Aliassime, all had first-round byes.