A faster mens 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, its 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.

"People like seeing the volleys, the return winners, the angles and all the reactions, but there is a bit too much dead time.

"We just looked at how we can keep the game flowing to make it a better product for the fans ultimately.

Those supporters will be able to move freely around the stadium during points.

Jamie Murray and his partner Michael Venus beat the singles team of Denis Shapovalov and Alexander Bublik in the first round on Tuesday.

Murray likes the shortened changeovers and the tournament being spread over such a short period, but is not a fan of the reduced time between some points.

I feel like its very rushed, the seven-time Grand Slam champion said after the match.

"Fifteen seconds for doubles is very short. In singles you are playing a lot on instinct, but in doubles theres a lot more strategy to start the points, and to lose that communication with your partner I dont think is a good thing for the sport."