Marin Cilic has withdrawn from Madrid, adding to the number of top players who will not be playing the tournament.
Roger Federer, Andy Murray, Stanislas Wawrinka and Serena Williams are among those not taking part. Other withdrawals include Jo-Wilfried Tsonga, Nick Kyrgios, and Andrey Rublev, along with Spain's David Ferrer, who just became a father and will not be competing next week.
Cilic, who got married a week ago, fell in the first round of Istanbul this week and said the injury had begun in Monte Carlo.
"I began feeling sharp knee pain back in Monaco and while I'm eager to compete, my team and I decided the best option is to pause and focus on rehab," the Croat said on Twitter.
