Denis Shapovalov serves against Frances Tiafoe on Wednesday in Toronto, Canada. Photo: VCG

Home hopes were dashed Wednesday at the ATP ­Toronto Masters as Canadians Denis Shapovalov and Felix Auger-Aliassime exited in the second round.

Fifth-seeded Shapovalov became the highest-ranked seed to actually lose a match - No.2 Rafael Nadal withdrew before playing - as he fell 6-1, 6-4 to good friend Frances Tiafoe.

Serbia's Dusan Lajovic defeated Auger-Aliassime 7-5, 6-4.

"I didn't feel like the conditions were easy, a little bit windy and the ball flying a bit off my racquet," Auger-Aliassime said.

"Every day conditions in tennis are a little bit different, you've got to try to adapt to them. I thought I served well, but the margins were pretty small.

"I just have to accept the situation, there's nothing more to do right now."

Shapovalov was buried by American Tiafoe, a lucky loser from qualifying who had lost four previous matches against his northern rival.

Shapovalov has now dropped three matches in a row, at Wimbledon and last month in the Swiss alpine village of Gstaad where he was top seed.

The Canadian threw in nine double-faults, producing a total of 30 unforced errors in the defeat.

"It was not an ideal performance, I'm not happy," Shapovalov said.

"I felt uncomfortable today against a guy with a few matches under his belt.

"I tried a lot of things but he was way more comfortable: you could see it was my first match and he's been here and playing already."

Tiafoe booked a third-round meeting with French veteran Gael Monfils, a 3-6, 6-3, 6-4 winner over Australian John Millman.

Monfils won only his fourth match since tennis resumed in August 2020 against 13 defeats.

His last win at Masters 1000 level was Paris Bercy in November, 2019. 

In other second-round action, Jannik Sinner fell flat after lifting the trophy in Washington on Sunday, the Italian losing 6-3, 6-4 to James Duckworth.

Just 72 hours after claiming the biggest title of his career, the 16th seed went down in his opening match against the Australian qualifier after enjoying a first-round bye.

Sinner, 19, is the youngest player ranked in the top 15 since Juan Martin del Potro in 2008 by virtue of his victory in the US capital.

But north of the border, his luck changed. Sinner exited in just over an hour and a quarter with the 85th-ranked Aussie securing the upset with one break per set.

Duckworth next plays top-seeded world No.2 Daniil Medvedev in the third round.

Fourth seed Andrey Rublev and fellow Russian Karan Khachanov, the Olympic silver medalist, reached the third round, Rublev beating Italy's Fabio Fognini 7-6 (7/4), 6-3.

Khachanov beat compatriot and 15th seed Aslan Karatsev 7-6 (9/7), 6-4.

Seventh seed Hubert Hurkacz reached the third round without hitting a ball, benefitting from Kei ­Nishikori's withdrawal with a shoulder injury.