The two-time ATP Finals champion hit eight double faults in losing 6-4, 6-2 to 81st-ranked Jiri Lehecka at Sydney’s Ken Rosewall Arena to give the Czech Republic a 1-0 lead in their tie against Germany.

It was Zverev’s first competitive match since tearing three right ankle ligaments during his Roland Garros semi-final against Rafael Nadal, when he left court in a wheelchair.

A planned return at the Davis Cup in September came up short when Zverev pulled out after experiencing “extreme pain”.

The Olympic champion, who has dropped to 12 in the world from a career-high two before his injury, was clearly still struggling against Lehecka.

He fended off break points at 2-3 in the first set but a double fault at 4-5 handed the Czech set point and he grabbed the opportunity, converting with a lob.

The German worked two break points in the first game of the second set, but blew the chance with some wayward shots.

With his serve not firing, he was broken to go 3-1 behind and despite breaking straight back couldn’t sustain the pressure with another double fault, helping Lehecka go 2-4 in front and there was no way back.

“I knew before the match that he didn’t play for a while but with a player like this, it can of course mean nothing,” said Lehecka, 21, after one of his biggest wins.

“I was able to show up in crucial moments. All the experience from last year, losing to good players, gave me the confidence to play against a player like him.”

The Czechs lost their opening tie in the tournament – a new 18-country mixed-teams event being held in Brisbane, Perth and Sydney – to the United States 4-1. Germany were making their first appearance.

Spain’s 22-time Grand Slam champion Nadal and Polish women’s world number one Iga Swiatek play later.

World number two Nadal opens Saturday’s second session in Sydney against Britain’s Cameron Norrie, ranked 14. They have played four times before, with Norrie yet to win.

Swiatek, who has led the rankings for 39 weeks, faces Yulia Putintseva of Kazakhstan at Brisbane’s Pat Rafter Arena, having won their only previous meeting in straight sets.