Defending champion Taylor Fritz won his Japan Open first round match on Tuesday and said he felt "motivated and ready to play" after lightening his load ahead of the tournament.

The American has been one of the busiest players on the ATP Tour this season but he has taken his foot off the gas since the US Open, appearing in only the Laver Cup and Shanghai Masters.

He beat Britain's Cameron Norrie 6-4, 6-3 to kick off the defence of his Tokyo title and said it was "probably an advantage that I might be less burnt-out".

"After the US Open, I think I had played the most matches of anyone on tour," said Fritz, the No 1 seed in Tokyo.

"I thought it made sense to start the Asia swing in Shanghai. I feel motivated and ready to play."

World number 10 Fritz beat fellow American Frances Tiafoe in last year's Japan Open final and has won six career titles.

He is the highest-ranked American in the world and overcame an early setback to dispatch Norrie in his Tokyo opener.

"I was holding easily and then out of nowhere he broke me, so it was a tough spot to be in," said Fritz.

"I feel like I played a couple of really good points to break and I played the bigger, more important points better in the return games.

"I definitely upped my level."

Fritz was joined in the next round by American Ben Shelton, who beat Japan's Taro Daniel 3-6, 6-4, 7-6 (7/2).

Australia's No 4 seed Alex de Minaur also progressed with a 4-6, 7-6 (7/4), 7-6 (7/1) win over Britain's Jack Draper.

Australia's Alexei Popyrin eliminated Russian No 7 seed Karen Khachanov 6-4, 6-2.

FIRST ROUND RESULTS

Taylor Fritz (USA x1) bt Cameron Norrie (GBR) 6-4, 6-3

Shintaro Mochizuki (JPN) bt Tomas Etcheverry (ARG) 6-4, 7-6 (7/5)

Christian Garin (CHI) bt Sho Shimabukuro (JPN) 6-4, 3-6, 6-3

Alexei Popyrin (AUS) bt Karen Khachanov (RUS x7) 6-4, 6-2

Alex de Minaur (AUS x4) bt Jack Draper (GBR) 4-6, 7-6 (7/4), 7-6 (7/1)

Diego Schwartzman (ARG) bt Francisco Cerundolo (ARG) 6-4, 6-1

Ben Shelton (USA) bt Taro Daniel (JPN) 3-6, 6-4, 7-6 (7/2)