The Madrid Open will be played as a two-week tournament from 2021.
The event was first played as an ATP Masters 1000 in 2002 and then moved from hard court to clay in 2009, as well as combining as a WTA Premier Mandatory event.
It will now undergo another significant change as it expands from a one-week event and will run from April 27 to May 9 next year.
"We’re happy to have achieved the goal of becoming a two-week tournament”, said tournament director Feliciano Lopez.
"We sought this expansion and it is well-deserved, necessary and will allow us to enjoy the best tennis in the world at the Caja Magica for a few more days. I’m sure that both our sponsors and all the fans will welcome this news with open arms, as well as the city of Madrid, which will receive more visitors for a longer period of time.”
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WTA chairman Steve Simon added: "The Mutua Madrid Open is held in incredibly high regard across the tennis community. This two-week format will allow the Madrid organisers to showcase this world-class event in the beautiful city of Madrid as truly one of the premier events on the WTA Tour and within the sport of tennis."
The tournament was not played in 2020 due to the Covid-19 pandemic but Novak Djokovic and Kiki Bertens are defending champions from 2019.