Nadal praises young Norwegian slammed as 'boring' by Kyrgios

Rafael Nadal said a bright future awaits "amazing" young Norwegian Casper Ruud, who has proved a giant-killer at the ATP Cup despite being slammed as "boring" by Nick Kyrgios.

The 21-year-old, a product of Nadal's tennis academy in Mallorca, has beaten top-20 players John Isner and Fabio Fognini to make his mark at the international teams tournament in Australia.

Ruud was catapulted into the spotlight last year after Kyrgios threw a temper tantrum during their match at the Italian Masters, hurling a chair on to the court.

He later blasted the combustible Australian as an "idiot" and "totally crazy", prompting Kyrgios to fire back that he would rather "watch paint dry" than "boring" Ruud.

"I saw (Ruud) playing good in the off-season, practising every single day in Mallorca and he was practising strong and very well," said Nadal, the world number one and 19-time Grand Slam winner.

"Yeah, it's very important to have a beginning of the season with these two great results winning against ..