British number one Cameron Norrie was beaten in straight sets by Alexander Zverev in Great Britain's ATP Cup opener with Germany after Dan Evans had got the team off to a winning start.
World number three Zverev won 7-6 (7-2) 6-1 in the pair's third meeting.
Earlier, British number two Evans breezed past Jan-Lennard Struff 6-1 6-2 to give GB an early lead in Sydney.
"I've been practising well, but I didn't expect to play the match this well," said Evans.
Zverev will return to court alongside Kevin Krawietz in the deciding doubles against Jamie Murray and Joe Salisbury.
Speaking after his win over Norrie, Olympic champion Zverev said: "The first match of the year is never going to be the best match of your life. But I'm pretty happy as I did my job. We're here to try and win."
This is the third edition of the ATP Cup, which features 16 countries competing in four groups at two venues in Sydney - the Ken Rosewall Arena and Qudos Bank Arena.
Earlier on day two, Russia's world number two Daniil Medvedev suffered a shock defeat by France's Ugo Humbert.
After Medvedev's team-mate Roman Safiullin had beaten Arthur Rinderknech in three sets in the opening singles rubber, world number 35 Humbert won 6-7 (5-7) 7-5 7-6 (7-2).
But Medvedev and Safiullin then won the deciding doubles tie 6-4 6-4 to ensure a 2-1 Russia win.
In the other tie in Britain's group, the United States beat Canada 3-0.