Medvedev ends run of giant-killer Ruud

World number five Daniil Medvedev ended Casper Ruud's giant-killing spree with a 6-3, 7-6 (8/6) victory on Tuesday to seal Russia's place in the quarter-finals of the ATP Cup.

The US Open finalist continued his ominous form ahead of the Australian Open, hitting 34 winners and 13 aces in the one hour 33-minute contest.

Medvedev wrapped up the tie for unbeaten Russia ahead of the doubles after world number 17 Karen Khachanov easily beat Viktor Durasovic 6-2, 6-1.

"Maybe the score doesn't say everything about the match because it was really close and both of us could have won," Medvedev said of his first-ever clash against Ruud.

The towering Russian was particularly impressive at the net, winning 14 of 19 points.

"Against Casper I knew I had to finish some points at the net," he said.

"I knew I had to be aggressive and I think it helped me a lot." Group D winner Russia advanced to the knockout stages in Sydney, while Norway's surprising run, which started with a stunning upset of the United States, ended.

Ruud, whose father Christian is Norway's captain and his coach, upset Italian world number 12 Fabio Fognini on Sunday after beating American John Isner, ranked 19, two days earlier.

The 21-year-old is a product of Rafael Nadal's tennis academy in Mallorca and has received high praise from the Spaniard, who dubbed him "amazing" on Monday.

Ruud continued to impress but was no match for Medvedev, who has steadily built his form after victories over Fognini and Isner.

Both players slugged relentlessly from the baseline in a high-quality contest, but Medvedev's consistency wore down the world number 53.

The Russian ripped several passing shots for winners and showcased his repertoire with deft drop shots as he dominated at the net.

Medvedev was under pressure in the second set and down an early break, but hit back on Ruud's serve in the fifth game before closing out the match in a tense tight break.

In the earlier singles, Khachanov breezed past world number 329 Durasovic.

He broke twice in a lopsided first set and kept the foot on the gas to maintain his unbeaten start to the season.

"Happy to start like this and I think match by match I'm playing better," said Khachanov, who defeated Italy's Stefano Travaglia and American Taylor Fritz earlier in the tournament.

Italy and the United States clash in the later Group D tie.