The 30 year-old improved his record to 24-0 with his 21st knockout at the Turning Stone Casino in Verona, dropping the previously un-moved Pole three times in the fight as he dominated proceedings.
The Kazakhstan fighter, on this form, would give problems to either of the two main fighters in the division in Chavez Jr. and Martinez, with a fight against the winner a mouth-watering prospect down the line.
Golovkin had Proksa in trouble from the off and looked bigger and stronger than ‘Super G’ in all departments, putting him on the canvas in the first, fourth and fifth rounds until referee Charlie Fitch waved the fight off.
Proksa, 27, could boast a crushing three-round victory over former world champion Sebastian Sylvester as his career-high going into the contest, but now drops back in the pecking order following his second defeat in three bouts.
In chief support, former world light-middleweight champion Sergey Dzinziruk fought out a draw with a bulked-up Jonathan Gonzalez as the judges scored the contest 117-111, 113-115, 114-114.