MONTREAL, Canada (AFP) — Wimbledon runner-up Nick Kyrgios let an early lead slip but regrouped on Tuesday for a 6-4, 6-4 first-round victory over Sebastian Baez at the ATP Montreal Masters.

World No. 37 Kyrgios, a title winner last week in Washington, next faces world No.1 Daniil Medvedev, who won last week's Los Cabos crown.

"It will be a great test and a lot of fun," Kyrgios said.

"He's a hell of a player. He's unorthodox — an animal."

"I want to see where my game's at so I'll be giving it my best shot."

The day was a disaster for Britain's Andy Murray as the treble Grand Slam winner was cut off in the first round, a 6-1, 6-3 victim of Taylor Fritz.

The American presented nothing but frustration to Murray, who lost with just seven winners and 19 unforced errors while Fritz fired 30 winners in 87 minutes.

"It's an honor to be on court with Andy," Fritz said.

"He has been dominating since before I came onto the tour."

Medvedev's chances of retaining the top ranking over the next month are on the line when he plays Kyrgios.

The 27-year-old Australian secured his seventh straight match victory since losing to Novak Djokovic in last month's Wimbledon final.

Kyrgios said he is on point physically but had to work to maintain mental strength in the match played 48 hours after lifting the trophy in the US capital.

"Physically I feel fine, mentally I'm tired," he said.

"I've not had much sleep in the last few days."