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Grigor Dimitrov of Bulgaria hits a backhand return to Roberto Bautista Agut of Spain during their fourth round match at the Australian Open tennis championship in Melbourne, Australia, Monday, Jan. 20, 2014.
MELBOURNE, Australia—Grigor Dimitrov has advanced to his first Grand Slam quarterfinal in his 14th attempt after beating Roberto Bautista Agut 6-3, 3-6, 6-2, 6-4 at the Australian Open on Monday.

Dimitrov, who beat No. 11 Milos Raonic in the third round, will play either top-ranked Rafael Nadal or Kei Nishikori in the last eight on Wednesday. He clinched the match by breaking Bautista Agut's serve for the fourth time.

The 22-year-old Bulgarian's breakthrough win came on the same day his girlfriend, Maria Sharapova, lost her fourth-round match to Dominika Cibulkova.