Andy Murray admitted he is not as fit as he should be after performing his latest act of escapology in Great Britain’s gruelling Davis Cup victory over the Netherlands in Madrid.

Murray’s 6-7 (7) 6-4 7-6 (5) win against 179th-ranked Tallon Griekspoor was the sort of comeback for which he has become famous.

Murray was 4-1 down in the deciding set and then in the same position in the tie-break but conjured up some remarkable defence to claw his way to victory in front of an enthusiastic crowd.

Dan Evans was beaten 3-6 7-6 (5) 6-4 by Robin Haase in the second rubber but Jamie Murray and debutant Neal Skupski won the tie, which lasted close to nine hours, with a 6-4 7-6 (6) victory over Wesley Koolhof and Jean-Julien Rojer in the deciding doubles.

Victory over Kazakhstan on Thursday would put Britain through to the quarter-finals in the new-look competition, but whether Andy Murray plays any part remains to be seen.

Griekspoor, 23, played well above his ranking but Murray was sluggish throughout, the sharp movement that was evident in his brilliant title victory in Antwerp a month ago sorely lacking.

The Scot admitted last week that he had put on a few pounds in the weeks since as the arrival of his son Teddy took his focus away from the court.

“I told you guys I wasn’t feeling in the best shape coming in, and it showed a little bit in the match,” he said.

“The weight and things like that, that’s my fault. I won’t put myself in that position again.

“If you’re weighing four or five kilos more than you’re used to, that is probably going to affect how you feel moving around the court.”

Murray looked exhausted at the end, while he also appeared to be struggling with a cold, so there is every chance that Kyle Edmund will play on Thursday instead.

Smith admitted he considered leaving the three-time grand slam champion out of this tie but hopes it will still prove a useful outing.

He said: “When you’ve got Andy in the team, when you’re trying to look at this competition as a whole and not to necessarily win one match but also to get some momentum going, to be used later in the competition as well.

“We thought, based on practice, based on obviously he’s won Antwerp. OK, it was a number of weeks ago, but it’s still suggesting that he’s going to be the right pick as the number two player. It might still work out.”

Murray was not helped by the Netherlands springing a surprise by selecting Griekspoor instead of Botic Van De Zandschulp, who Britain had been preparing for.

Great Britain’s captain Leon Smith, left, talks with Andy Murray during the game
Great Britain’s captain Leon Smith, left, talks with Andy Murray during the game (Bernat Armangue/AP)

Murray denied the British team had taken this match lightly but conceded the result could easily have gone the other way.

“He played brilliant,” said the Scot. “I was lucky at the end of the match. He deserved to win.

“It is about finding a way to win, and I did that today. And I’m proud of myself because it would have been easy to have lost that.”

British number one Evans looked to be in a winning position at a set and a break up and he served for the match at 5-4 in the second set only for Haase, a former top-40 player currently ranked 163, to mount a fightback.

That put the pressure on Jamie Murray and Skupski, who have formed an encouraging partnership since linking up in June.

Skupski’s older brother Ken played in Smith’s first Davis Cup tie in 2010 and he tweeted his pride as Neal produced a fine performance, coming up with big shots at the important moments.

Jamie Murray said: “We did really well to win today. It was a really tough match against a really good doubles team. We knew it was going to be a battle.

“Obviously Evo (Evans) played a really good match, got himself into a position to win. We were like: ‘OK, it’s going to be 2-0’, our match doesn’t maybe have the same pressure, and then an hour later we were playing and it all comes down to that match.

“You feel: ‘OK, on the first day we could maybe be out of the competition’. So I think we did a great job to stay focused and play to a level that we did. And of course, for Neal to do that in his debut I think was really impressive.”

On paper, Kazakhstan will be a sterner test with two top-100 players in Mikhail Kukushkin and Alexander Bublik.