Isner, the top seed playing on a wild card invitation as he continues his return from a foot injury, booked a final-four showdown with fourth-seeded Frenchman Ugo Humbert, a 7-5, 3-6, 6-2 victor over Ilya Ivashka of Belarus.
After an early exit at Wimbledon, the three-time Newport champion John Isner has chose to return to the Fall of Fame Open, battling past the first two opponents to advance into the semis.
"It's my first final and I'm going to remember this day forever", said Bublik. "I actually didn't see the ball land in because my face was on the ground".
"You're very quirky but I mean that in a very honest way".
The Kazakh earned five breaks, playing better and better as the match progressed to secure the spot in the first ATP semi-final.
John Isner of the U.S. and Ugo Humbert of France compete in a semi-final of the Hall of Fame Open at the International Tennis Hall of Fame in Newport, Rhode Island, U.S., July 20, 2019.
The match started in blazing sunshine with a temperature of 85 degrees and a feel-like temperature of 95.
Facing a creative opponent who mixed in numerous underhanded serves, with cuts and slices throughout the match, the 34-year-old American captured his 15th ATP title overall.
The opening set lasted for more than an hour and Humbert wasted the opportunity to clinch it on own serve at 5-4, having to chase another break before a hold at 30 that carried him towards a 7-5.
"Two sets in that stuff is still very hard", said Isner, who entered the week ranked 15th in the world. Isner double-faulted early in the second-set tiebreaker, but won five straight points as he rallied to level the match - firing a stinging backhand victor on his second set point. "I'm just glad I won a match".
"If you break, you've got to hold", Bublik said of facing Isner's hard serve. "If you don't hold it, you're over". But Isner won the final two games of the second set and the tiebreaker before being the stronger player in the final set.
"It's hot", said Bublik when asked about the conditions during a post-match interview on the court. "I was like: 'I'm not going to do anything, just a fake overhead.' That was amusing".