Knee pain has knocked Marin Cilic out of Madrid.
The world No. 4 announced he's withdrawn from next week's Mutua Madrid Open due to knee pain.
More: Jaziri Upsets Cilic in Istanbul
The 2014 US Open champion tweeted he began feeling "sharp knee pain" in Monaco.
Cilic, who reached the Monte-Carlo quarterfinals last month, cited a stiff knee in his 6-4, 6-2, loss to Malek Jaziri in Istanbul yesterday. Cilic was the defending Istanbul champion.
The 29-year-old Croatian has not surpassed the round of 16 in nine Madrid appearances, including an opening-round loss to Alexander Zverev last May.
The Australian Open finalist did not set a date for his return.
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