SYDNEY: Denis Shapovalov put Canada within one win of reaching the ATP Cup final for the first time with a battling 6-4 5-7 6-4 victory over Russia's Roman Safiullin on Saturday.

A depleted Russia, who beat Italy in last year's final, came into the $10 million tournament without fifth-ranked Andrey Rublev and world number 18 Aslan Karatsev after both tested positive for COVID-19 in the lead-up to the team event.

Russia's hopes of defending their ATP Cup title now rest on the shoulders of world number two Daniil Medvedev, who will meet 11th-ranked Felix Auger-Aliassime in the second singles rubber at the Ken Rosewall Arena.

The winner of the tie will meet Spain in Sunday's final.

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In his first career meeting against the 167th-ranked Safiullin, the left-handed Shapovalov dominated proceedings to take the opening set, but the gritty Russian levelled things after his opponent hit an overhead smash into the net.

Safiullin looked set to force ahead for an upset win against the 14th-ranked Shapovalov when he had six breakpoints at 2-1 in the deciding set. But the 22-year-old saved all of them to hold serve and then used the shift in momentum to break for 4-3.

Shapovalov, who had contracted COVID-19 in the lead-up of the ATP Cup, did not look back from there and completed the win in two hours and 39 minutes to give Canada a 1-0 lead.

"Definitely super tough. Obviously Roman is playing with a lot of confidence," Shapovalov said. "He's a great player and surely he's going to have an amazing season, so I'm very happy to get the win. It was definitely very tough.

"He's shown this competition that he definitely should be ranked in the Top 100. The way he was playing today, it was top-10, top-20 tennis, it was incredible."