Briedis progressed through to the World Boxing Super Series Final with the win, moving his record to 26-1.
The defeat over Glowacki was a controversial one, however, after a series of questionable incidents.
At the end of the first round, Glowacki caught Briedis with a stiff left hand while the two were in a clinch.
In retaliation, the Latvian fighter threw a vicious elbow which would not have looked out of place in a UFC contest, connecting with the chin of the Polish challenger.
The sheer power of the elbow sent Glowacki crashing to the canvas face down, but staggeringly referee Robert Byrd simply strolled over and demanded that the fallen boxer get up, saying: “Get up. Let’s go, get up.”
Byrd took a point away from Briedis, before telling the fighters to keep the bout clean.
Seconds after the two fighters were brought together again, Glowacki hit the deck again after a legitimate punch, but after he returned to his feet, the drama continued.
Both fighters continued swinging punches at each other for more than ten seconds with the bell ringing frantically, as fans and officials ringside could be seen waving at the referee to signal the end of the round.
Byrd did not hear the bell, however, and Briedis landed a perfect three-punch combination to send Glowacki to the floor once again.
Despite it seeming that Byrd was about to call the fight off, he instead allowed the fighters to return to their corners for the end of the round.
Whilst the first two rounds were filled with controversy, the finish was conclusive, as he rocked the challenger yet again before knocking him down hard. Glowacki returned to his feet but with unsteady legs, as Byrd waved off the bout.
Speaking afterwards, Briedis stunningly admitted that he had, in fact, heard the end of the round.
“The end of the round, he hit me with a punch behind the head that the referee did nothing, then it got a bit dirty,” he told Sky Sports.
“No, I heard the bell.”
Promoter Kalle Sauerland insisted that the referee had not heard the bell, whilst suggesting that the fighters hadn’t either.
“It was a crazy one, eh?” he told Bradley Cullen.
“There was such an atmosphere here tonight that there were loads of Polish fans, famous for their noise, and Latvian fans, it was crazy.
“The referee didn’t hear the bell, the fighters didn’t hear the bell at the end of the fourth.
“Briedis landed some telling shots, obviously Glowacki caught him with one as well, but then Briedis put him to sleep.”