The 22-year-old Kazakhstani hit 35 aces to beat fourth-seeded Bulgarian Grigor Dimitrov 5-7, 7-6(9), 7-6(3) in two hours and 32 minutes at the ATP 250 tournament. It denied Dimitrov his 300th match win.
Bublik saved two match points at 6/7 and 8/9 in the second set tie-break, which he clinched on his third set point. He then won the first three games of the deciding set and held a 4-1 advantage, before Dimitrov battled back to 4-4 and saved one match point at 4-5, 30/40. Bublik won the first five points of the deciding set tie-break.
World No. 71 Bublik has now hit 73 aces in three matches at the ATP 250 tournament – including 25 aces against Taylor Fritz in the first round, 13 aces against Jordan Thompson in the second round. He will next face South African lucky loser Lloyd Harris or Joao Sousa of Portugal.
Bublik advanced to his first ATP Tour final in July at the Hall of Fame Open in Newport (l. to Isner) and is now 13-10 on the season. Dimitrov reached his third Grand Slam championship semi-final earlier this month at the US Open (l. to Medvedev).