Tsitsipas and Sakkarri, who thrashed Daniela Seguel 6-0 6-1 in the women’s singles, fell 6-7 (7-5) 6-3 10-6 to Seguel and Tomas Barrios Vera in the mixed doubles.

Nicolas Jarry had earlier survived a scare at the hands of Tsitsipas’s replacement - towering 19-year-old Stefanos Sakellaridis - to claim a 6-3 3-6 7-5 victory before Chile went on to secure a 2-1 win across the tie.

And, while Sakellaridis’s performance against a player ranked close to 400 places above him was impressive, Tsitsipas’s fitness will be a huge concern ahead of the Australian Open.

The Greek, who was runner-up to Novak Djokovic in Melbourne last year, hadn’t played since withdrawing from an ATP Finals meeting with Holger Rune in Turin last November due to a back injury but he insisted he wasn’t overly concerned by his latest flare up. 

“I’m much better than what I was a month ago,” Tsitsipas said. 

“I wasn't 100 per cent sure that I would have the chance to play the United Cup and it didn't really cross my mind when I was considering my comeback. 

“I went through tough times… Today, I was feeling great but there was just one moment during the match that I felt something.

“I don’t think I should be concerned about it too much, it's not a major issue that I'm facing.”

Asked if had hopes of featuring in both the men’s singles and mixed doubles in Greece’s Group B tie with Canada on Wednesday, Tsitsipas said: “There’s a chance I might do both.” 

Greece now need to beat the Canadians to have a chance of qualifying for the quarter-finals.

While the Greeks retain a glimmer of hope, Norway later topped Group F to advance without hitting a ball on Tuesday night.

The Netherlands' mixed doubles win in a match tiebreaker in a 2-1 defeat to Croatia was enough for Norway to progress.

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