Dominic Thiem, Nick Kyrgios, Elina Svitolina and Kiki Bertens will compete in grass and hard-court events in Berlin in July featuring both men's and women's fields.

The behind-closed-doors competition will be held on grass at the Steffi Graf Stadium from July 13-15 and then switch to hard court in a hangar at Berlin's Tempelhof Airport from July 17-19.

With Wimbledon cancelled for the first time since World War II due to the coronavirus pandemic, this will be the first grass-court tennis of 2020. Six men and six women are set to take part.

"I am curious to see where I stand with my tennis," said Germany's Alexander Zverev, who joins Austria's Thiem, the highest ranked at third in the world, and Australia's Kyrgios in the men's event.

"I've been practising hard, but it's going to be my first time playing a competitive event in a long time.

"It's going to exciting to play on two different surfaces in seven days."

In the women's field, Germany's Julia Goerges and Andrea Petkovic will join Svitolina of Ukraine and Bertens of the Netherlands, who are both in the top 10.

There will be no live spectators, electric line-calling will be used instead of judges and the matches will be played over two sets with a possible third as a tie-breaker.

The matches will be broadcast with prize money of 200,000 euros ($222,000) at stake -- 100,000 each for the men's and women's events.

The ATP and WTA tours are both suspended until late July due to the global health crisis.

The Steffi Graf Stadium was due to host the first WTA event of the grass season from June 13-20, but this year's tournament was cancelled following the virus outbreak.

Historic Tempelhof Airport has been closed since 2008, but the grounds remain open as a public park and was where planes landed during the Berlin Airlift in 1948-49.