Rafael Nadal lost 6-4, 6-4 to Germany's Alexander Zverev in the Madrid Open quarter-finals on Friday, casting doubts over the Spaniard's form ahead of this month's French Open. Nadal has now fallen early in two clay-court Masters tournaments ahead of the Grand Slam in Paris, after going out in the Monte Carlo quarter-finals last month before winning in Barcelona. World number two Nadal will be bidding for a 14th Roland Garros title and record-setting 21st major in the French capital. ta/dj