20-time Grand Slam champion Roger Federer could return to tennis in July at a grass-court exhibition event in Berlin.
There are currently plans for Berlin to host two three-day events with six men and six women, the first on grass at Steffi Graf Stadium and the second on hard courts in an airplane hanger. The events will each offer €200,000 in prize money.
The men's field already includes top stars Dominic Theim, Alexander Zverev, Nick Kyrgios and Jannik Sanner, with two more players set to join.
"We'll of course also ask Roger Federer," said organiser Edwin Weindorfer.
Federer has not played competitively since undergoing knee surgery after the Australian Open in January. He was set to return for the grass-court season before coronvairus put the tennis calendar on hold.
At least half a dozen exhibition events to be played behind closed doors have already been planned across Europe while competitive tennis remains suspended.
Germany's Angelique Kerber has been asked to join a women's field already including Elina Svitolina, Kiki Kertens, Julia Goerges and Andrea Petkovic.