Spanish tennis player Rafael Nadal in action against Russian Andrey Kuznetsov during their Mutua Madrid Open tennis tournament first round match at the Caja Magica Tennis Center in Madrid, Spain, 03 May 2016. The Mutua Madrid Open runs from 29 April until 08 May 2016. EPA/J. J. GUILLEN

Spanish tennis player Rafael Nadal in action against Russian Andrey Kuznetsov during their Mutua Madrid Open tennis tournament first round match at the Caja Magica Tennis Center in Madrid, Spain, 03 May 2016. The Mutua Madrid Open runs from 29 April until 08 May 2016. EPA/J. J. GUILLEN

Spanish tennis player Rafael Nadal returns the ball to Russian Andrey Kuznetsov during their Mutua Madrid Open tennis tournament second round match at the Caja Magica Tennis Center in Madrid, Spain, 03 May 2016. The Mutua Madrid Open runs from 29 April until 08 May 2016. EPA/CHEMA MOYA

Spanish tennis player Rafael Nadal in action against Russian Andrey Kuznetsov during their Mutua Madrid Open tennis tournament first round match at the Caja Magica Tennis Center in Madrid, Spain, 03 May 2016. The Mutua Madrid Open runs from 29 April until 08 May 2016. EPA/J. J. GUILLEN

Spanish tennis player Rafael Nadal celebrates his victory over Russian Andrey Kuznetsov in their Mutua Madrid Open tennis tournament second round match at the Caja Magica Tennis Center in Madrid, Spain, 03 May 2016. The Mutua Madrid Open runs from 29 April until 08 May 2016. EPA/JUANJO MARTIN