A faster men’s doubles format, with greater focus on matches between singles players and established doubles teams, is being trialled at the Madrid Open.
Teams are allowed just 15 - rather than the usual 25 - seconds between points after rallies up to three shots, and only 60 seconds to sit down at the change of ends.
Daniil Medvedev and Stefanos Tsitsipas were among seven top-20 singles players to enter the event, which features five rounds in just five days.
"For me, it’s a shootout, which is kind of exciting. Once we get going - bang, this is on," said Matt Ebden, the current doubles world number one and president of the ATP Player Council.