Kyrgios then struck a down the line backhand winner to reach 15-40.
Opelka netted a crosscourt slice backhand as Kyrgios scored one of the only two breaks of serve of the night to
lead 4-3 before taking the set.
In set two, both players struck powerful groundstrokes in an attempt to control the baseline rallies.
With his serve, Kyrgios preferred to strike powerful aces down the tee while Opelka mixed up the placement of his serves which reached speeds up to 136 miles per hour as the players entered the set two tiebreaker.
Opelka took the first tiebreaker point with a serve and volley play which ended in a crosscourt backhand volley winner.
The 6 feet 4 inches tall Kyrgios then struck two consecutive aces to lead 2-1.
The 6 feet 11 inches tall Opelka struck his next two serves at speeds of 137 miles per hour and 141 miles per hour to lead 3-2.
Then at 4 all in the tiebreaker a controversy erupted after Opelka hit a powerful serve out wide which forced a defensive high and short return from Kyrgios.
Opelka ran to the net and stuck a powerful crosscourt forehand winner to lead 5-4.
Kyrgios complained to the chair umpire that Opelka's foot touched the net while he stuck the forehand (which is not allowed) and the umpire had not called it.
"He touched the net. You didn't say s---," Kyrgios said. "That's bulls---."
A network broadcast video replay of the point wasn't as clear as could be but showed the net didn't move, which it most likely would have if Opelka had touched it.
Kyrgios hit a tennis ball high into the stands above the crowd after netting a down the line forehand on the following point which earned him a ball abuse code violation from the chair umpire.
A Kyrgios doublefault ended the otherwise spectacular second set and tied the match at one set all.
Kyrgios then continued his argument with the chair umpire on the following changeover.
"I saw his foot touch the net," Kyrgios said. "What are you watching?"
Then serving in the final set at 1 all, the Australian netted a crosscourt forehand before double faulting to trail 15-30.
Opelka; whose forehand improved greatly from set one to midmatch, then struck down the line forehand return winner before Kyrgios sent a down the line backhand long to drop serve and trail 1-2.
Serving ahead 4-3 30-0, Opelka struck a powerful down the line backhand winner which he followed up with a 98 miles per hour second serve out wide which landed for an ace.
Kyrgios saved two match points in his following service game to hold serve and reach 4-5.
However, serving for the match, Opelka struck a down the line forehand volley winner to lead 15-0.
The American followed up with a 128 miles per hour ace down the tee, his 22nd and final ace, to lead 30-0.
Kyrgios netted a backhand return off of an Opelka into the body serve to set up match point number three.
Opelka struck a powerful down the line forehand winner to end the one hour and 57 minutes long match.