The third set saw Fritz, who had to serve second, under fire as early as the third game; the 27-year-old dug out of a 15-40 deficit and held firm as scoreboard pressure continued to build.
Mensik held to love for 5-4 but Fritz won a thrilling rally two points from defeat. Undeterred, Mensik, who struck 21 aces to beat Draper earlier in the week, upper his total to 24 as he again moved within one game of victory.
Twice more forced within two points of defeat for a second time, Fritz rose to the challenge once more, stretching Mensik out wide to force an error. Mensik narrowly missed a backhand up the line and the match went to a decisive tiebreaker.
Much like the first set, Mensik nabbed the first mini-break but another backhand miss brought the Sudden Death back on level terms by the change of ends.
Two lengthy rallies ultimately decided the match: up 5-4, Mensik outlasted Fritz on both to edge over the finish line and book his first Masters final and his second meeting with Djokovic. His last match against the 24-time Grand Slam champion went the distance, but Djokovic emerged victorious in three sets last fall at the Rolex Shanghai Masters.