Top seed Taylor Fritz was among the seeds that tumbled out of the Japan Open.

Arthur Fils claimed the biggest scalp of the day in Fritz, the Frenchman playing some excellent tennis to run out a 6-4 3-6 6-3 winner and set up a meeting with Italy's Matteo Berrettini in the second round.

Three other seeds fell on a day of upsets, third seed Casper Ruud of Norway was beaten by Australia's Jordan Thompson in the late match, Greek fourth seed Stefanos Tsitsipas lost to Alex Michelsen of the united states while American seventh seed Frances Tiafoe fell 7-5 6-3 to his compatriot Brandon Nakashima.

Defending champion Ben Shelton survived but had to fight hard to make the second round, the American came back from a set down to beat his compatriot Reilly Opelka 3-6 6-16-4.

Sixth seed Holger Rune of Denmark fought his way through, coming out on top of Chile's Alejandro Tabilo.

Britain's U.S. Open Semi-Finalist Jack Draper saw off Italy's Mattia Bellucci 6-4 6-2 to earn his second round spot.