Nadal had won all seven of the pair's previous meetings, but failed to hold his serve once in a remarkable first set which started with five consecutive breaks.

It took more than half an hour before the first service hold gave Dimitrov a 4-2 lead and the 25-year-old then broke Nadal for the fourth time before serving out the set with the aid of his third ace.

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Dimitrov broke Nadal again at the start of the second set and although the former world number one saved more break points in each of his next three service games, he was unable to convert two of his own in the eighth game and Dimitrov went on to complete an impressive 6-2 6-4 success.

Dimitrov will face Milos Raonic in the last four after the third seed defeated Spain's Pablo Carreno Busta 6-4 6-4, while the other semi-final sees top seed Andy Murray take on David Ferrer.

Murray found an extra gear when it mattered to beat Davis Cup team-mate Kyle Edmund 7-6 (11/9) 6-2, while Ferrer recovered from a set down to beat Alexander Zverev.

Double Olympic champion Murray edged a tight first set in a tie-break and trailed 2-0 early in the second, but reeled off six games in a row to advance to the last four.

Ferrer fought back from 4-1 down in the opening set to Zverev before losing it on a tie-break, but the Spaniard dominated proceedings in the second set and went on to win 6-7 (4/7) 6-1 7-5.

The semi-final line-up was also completed in the Japan Open in Tokyo as Gael Monfils, Marin Cilic, David Goffin and Nick Kyrgios all enjoyed victories on Friday.

Australian sixth seed Kyrgios cruised past Gilles Muller 6-4 6-2, firing 18 aces to set up a last-four clash with Monfils, who edged past Ivo Karlovic 7-6 (8/6) 7-6 (8/6).

"I thought I played great today," Kyrgios said. "I served well, returned well and my engagement level was really good the whole time."

Cilic had earlier beaten Juan Monaco 7-5 6-1, while Goffin was made to work much harder before defeating Joao Sousa 1-6 7-5 6-2.

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