Alex de Minaur failed to take advantage of a fast start and Rafael Nadal’s late scratching as Australia lost their opening ATP Cup tie to Spain.

De Minaur was scheduled to take on world No.2 Nadal on Tuesday night, but the 20-time grand-slam winner withdrew just before the tie started with a stiff lower back.

It meant Spain’s No.3 ranked player – world No.16 Pablo Carreno Busta – was called up to play John Millman in the first singles match.

Millman showed plenty of fighting spirit but he was no match for Carreno Busta in a match that lasted just 77 minutes, with the Spaniard winning 6-2 6-4.

World No.23 de Minaur needed to beat world No.13 Roberto Bautista Agut to keep the tie alive, and he made a scintillating start to race out to a 5-1 lead.

The 21-year-old was broken twice in the next three games but was still able to seal the first set.

But from there Agut took control, snaring early breaks in each of the next two sets to secure the 4-6 6-4 6-4 win in two hours 20 minutes.

“Everybody knows Alex. He’s a great fighter, great player,” Agut said during his on-court interview.

“He just came from winning a tournament, so he was confident. It took me a while to get the rhythm of the match and I just wanted to fight when I was down 5-1 in the first set.

“It’s never easy to start a season. It’s always a little bit more nervous the first match. I fought well and I found my rhythm and I finished the match playing well.”

Carreno Busta was thrilled to get the late call up and come away with the win over Millman.

“Obviously it’s a situation where you are one of the best players in the world but you have two better players in your team,” he said.

“We’re so lucky to have Rafa in the team.

“I think it was a really good match for me. After the quarantine, the first match of the season is always tough to play.

“I felt comfortable, more comfortable than I can imagine, so I’m happy for this.”