World number four Stefanos Tsitsipas crashed to defeat in his first singles match since elbow surgery Monday, losing an epic battle with feisty Argentinian Diego Schwartzman 6-7 (5/7) 6-3, 6-3 at the ATP Cup.
The Greek star went under the knife in late November after pulling out of the ATP Finals in Turin, hoping to be at full fitness for the Australian Open later this month.
He was scheduled to return against world number nine Hubert Hurkacz at the teams event on Saturday, but withdrew before the match, opting instead to ease himself back in a doubles rubber.
He showed up to play 11th-ranked Schwartzman and looked at his battling best in winning the first set tiebreak, moving freely with little sign of his right elbow causing problems.
But the 23-year-old lost his focus, and with it, five games in a row.
After being broken in the second set, there was no way back on a humid Sydney evening.
“It’s his first match for two months after surgery and I was just thinking if the match was going to go long I had a chance,” said Schwartzman after the 2hr 42min battle that helped Argentina win their second ATP tie after beating Georgia on day one.
“I was ready for that and I think everything is going very well, playing Stefanos is not easy.”
Federico Delbonis had earlier continued his perfect start to the season by overcoming Greek number two Michail Pervolarakis 7-6 (7/5), 6-1 to give Argentina a 1-0 lead.
In morning action, Hurkacz ensured Poland also went 2-0.
But the world number nine was forced to dig deep against Georgian Aleksandre Metreveli, ranked just 570, who stepped in after Nikoloz Basilashvili was a no-show.
Once he found his groove, though, last year’s Miami Open champion raced to a 6-7 (5-7), 6-3, 6-1 victory.
“He played well in the first set and things were not going my way. But I got better with each set and am happy to get the win,” Hurkacz said.
Kamil Majchrzak gave Poland a strong start when he dropped just two games against Aleksandre Bakshi, winning 6-1, 6-1 in 53 minutes.
Whoever wins between Poland and Argentina on Wednesday will make the semi-finals, with only the top nation from each of the four groups progressing to the knockouts.
Veteran Roberto Bautista Agut, meanwhile, upset Norwegian world number eight Casper Ruud to give Spain their second straight win.
The 33-year-old Bautista Agut is the lead singles player for his country in the absence of 20-time Grand Slam champion Rafael Nadal and has stepped up in style.
After crushing Chile’s world number 17 Cristian Garin in Sydney on Saturday, he backed it up with a battling 6-4, 7-6 (7/4) victory over Ruud, the first Norwegian to win an ATP Tour title.
“I played very good with very few unforced errors,” said 19th-ranked Bautista Agut. “It’s a good start (to the season) and I’m feeling good.”
It ensured Spain won the tie with an unassailable 2-0 after Pablo Carreno Busta made a quick start when he dismissed Norway’s 345th-ranked Viktor Durasovic 6-3, 6-3 in just 69 minutes.
Former top-10 star Carreno Busta is now 4-1 in singles in his ATP Cup career, having beaten Chile’s Alejandro Tabilo on Saturday.
“It’s always important to win the first match. Today I felt more and more comfortable than the first day,” he said. “We need to get the rhythm, we need to get the confidence.”