Baghdatis ousted third-seeded Gilles Simon 6-3, 6-4. He won about two-thirds of the points on serve and saved four of the five break chances Simon had. He also finished off half of his six break opportunities.
Dimitrov beat No. 7-seeded Jurgen Melzer in 59 minutes. Dimitrov fired 17 aces at Melzer and won 70 percent of the points when serving. He didn't lose his serve and was 3-of-3 in break-point chances.
Top-seeded defending champion Andy Murray got by Denis Istomin 6-4, 7-6 (7-3) in the longest of the Brisbane quarterfinals. There was just one break in the match -- by Murray in the first set -- and there were no break opportunities for either player in the second.
Fifth-seeded Kei Nishikori edged by No. 4-seeded Alexandr Dolgopolov, the 2012 Brisbane runner-up, by the same 6-4, 7-6 (7-3) score. Nishikori had a break in each set but advanced by taking the tiebreaker.
Murray and Nishikori draw each other in Saturday's semifinals. Murray is 2-0 against Nishikori. Baghdatis and Dimitrov have split their two career meetings.