Emerging youngster Casper Ruud notched up the biggest victory of his career, beating big-serving John Isner, on Friday to spearhead Norway's stunning upset over the United States on the first day of the inaugural ATP Cup.
The 21-year-old levelled the Group D tie with a 6-7(3), 7-6(10), 7-5 win over the World No. 19 in two hours and 43 minutes.
He saved two match-points in the second set and weathered 33 aces from Isner, after Taylor Fritz thrashed Viktor Durasovic 6-2, 6-2 in the opening match in Perth.
Ruud then backed up in the decisive doubles alongside Durasovic to down Rajeev Ram and Austin Krajicek 4-6, 6-3, 10-5 and trigger jubilant scenes from the Norwegian contingent.
The World No. 54 has risen up the rankings over the past year since training alongside Rafael Nadal at the World No. 1's academy in Mallorca.
Ruud, whose father Christian is Norway's captain, clawed back into the match and stormed out to a 6-4 lead in the second set tiebreak, but was thwarted on his set-points by a desperate Isner.
He saved two match-points in a see-sawing set before finally converting on his fifth attempt to keep Norway alive.
It appeared the match was going the distance in the third set until an inspired Ruud broke in the 12th game to clinch his first victory over a top-20 ranked player.
Earlier, World No. 32 Fritz gave heavily favoured United States the perfect start with a commanding victory over Durasovic in 61 minutes.
Fritz — ranked 300 places higher — unleashed his big serve with 11 aces and returned accurately to underline the gulf in rankings. The match was played under the roof due to unusually cool and damp morning conditions here.
Meanwhile, Alexander Zverev and Stefanos Tsitsipas crashed to defeats in their first matches of the year.
The German World No. 7 was stunned by Australia’s fast-improving Alex de Minaur, who rallied from a set and 4-2 down to win 4-6, 7-6(3), 6-2. Greek star Tsitsipas slumped to a 7-6(6), 7-6(4) loss to young Canadian Denis Shapovalov.
It led to both Germany and Greece being defeated in their opening ties at the 24-nation event, where the countries are split into six groups across Sydney, Brisbane and Perth.
The results:
In Sydney: Group C: Belgium 3 bt Moldova 0 [Steve Darcis bt Alexander Cozbinov 6-4, 6-7(4), 7-5; David Goffin bt Radu Albot 6-4, 6-1; Sander Gille & Joran Vliegen bt Radu Albot & Alexander Cozbinov 6-7(5), 7-6(4), 11-9].
In Brisbane: Group F: Canada 3 bt Greece 0 [Felix Auger-Aliassime bt Michail Pervolarakis 6-1, 6-3; Denis Shapovalov bt Stefanos Tsitsipas 7-6(6), 7-6(4); Denis Shapovalov & Felix Auger bt Petros Tsitsipas & Pervolarakis 6-2, 6-3].
Australia 3 bt Germany 0 [Nick Kyrgios bt Jan Struff 6-4, 7-6(4); Alex de Minaur bt Alexander Zverev 4-6, 7-6(3), 6-2; Chris Guccione & John Peers bt Kevin Kravietz & Andreas Mies 6-3, 6-4].
In Perth: Group D: Norway 2 bt USA 1 [Viktor Durasovic bt Taylor Fritz 6-2, 6-2; Casper Ruud bt John Isner 6-7(3), 7-6(10), 7-5; Ruud & Durasovic bt Rajeev Ram & Austin Krajicek 4-6, 6-3, 10-5].
