Madrid Open: Rafael Nadal beaten by Dominic Thiem as unbeaten run ends
Rafael Nadal's 21-match unbeaten run on clay ended as he was knocked out of the Madrid Open in the quarter-finals by Dominic Thiem.
Spaniard Nadal, who had not lost a set and was unbeaten on the surface since defeat by Austrian Thiem in May 2017, lost losing 7-5 6-3.
Nadal, 31, set a record of 50 consecutive sets won on one surface on Thursday.
His defeat means Swiss Roger Federer will replace Nadal as world number one.
Federer has not played since 24 March and sat out the clay-court season, but Nadal will lose the ranking points from his win in Madrid last year when the list is updated on Monday.
Thiem will play South African Kevin Anderson in the semi-final.
Five-time Madrid champion Nadal was below his best, hitting 29 unforced errors in the two sets, but Thiem produced a fine performance.
He failed to convert break points in the first game of the match but broke Nadal's serve in the seventh game to take a 4-3 lead.
Nadal saved a set point before breaking back for 5-5 but Thiem won the following two games to close out the set.
Thiem won an enthralling nine-minute game to break serve and take a 2-1 lead in the second set and, despite Nadal levelling at 3-3, Thiem broke serve twice more en route to clinching the match.
BBC tennis correspondent Russell Fuller
Thiem had not beaten Nadal on clay for 357 days - and neither had anyone else.
The Austrian made a slow start to his favourite season of the year, but played a magnificent match and smashed many memorable off forehand winners past Nadal.
The Spaniard was not able to play at his usual level, and this is not his favourite venue. Madrid is about 650 metres above sea level, so the ball flies through the air. He has only won this title four times since it has been played on clay: in contrast, he has won 11 times in Monte Carlo and Barcelona, and will be chasing an 11th French Open title later this month.
The men's game desperately needs someone to threaten some sort of rivalry with Nadal on clay, but the Spaniard remains a hot favourite for Roland Garros and will be world number one again if he wins in Rome next week.