On April 21, 2018, a 30-year-old Mateusz Masternak (40-4, 27 KOs) and Youri Kayembre Kalenga met in the ring for the 2nd time, in a cruiserweight bout.
Masternak came in to the fight on a 4-fight win streak with a 61% KO rate, and was fighting after a gap of 6 months.
In the rematch, Mateusz Masternak stopped Youri Kayembre Kalenga via RTD in the 6th round. Masternak improves his record to 41-4 (28 KOs)
On September 10, 2011, a 24-year-old Mateusz Masternak (23-0, 17 KOs) and Carl Davis met in the ring.
Masternak came in to the fight on a 23-fight win streak with a 73% KO rate, and was fighting after a gap of 2 months and 16 days.
Mateusz Masternak stopped Carl Davis via TKO in the 3rd round. Masternak improves his record to 24-0 (18 KOs)
On March 11, 2011, a 23-year-old Mateusz Masternak (21-0, 15 KOs) and Ali Ismailov met in the ring.
Masternak came in to the fight on a 21-fight win streak with a 71% KO rate, and was fighting after a gap of 4 months and 6 days.
Mateusz Masternak stopped Ali Ismailov via TKO in the 5th round. Masternak improves his record to 22-0 (16 KOs)
On February 4, 2012, a 24-year-old Mateusz Masternak (24-0, 18 KOs) and Michael Simms met in the ring.
Masternak came in to the fight on a 24-fight win streak with a 75% KO rate, and was fighting after a gap of 4 months and 25 days.
Mateusz Masternak stopped Michael Simms via TKO in the 4th round. Masternak improves his record to 25-0 (19 KOs)
On October 24, 2009, a 22-year-old Mateusz Masternak (14-0, 9 KOs) and Łukasz Janik met in the ring.
Masternak came in to the fight on a 14-fight win streak with a 64% KO rate, and was fighting after a gap of 3 months and 13 days.
Mateusz Masternak stopped Łukasz Janik via TKO in the 5th round. Masternak improves his record to 15-0 (10 KOs)
On July 11, 2009, a 22-year-old Mateusz Masternak (13-0, 8 KOs) and Mazur Ali met in the ring.
Masternak came in to the fight on a 13-fight win streak with a 61% KO rate, and was fighting after a gap of 4 months and 27 days.
Mateusz Masternak stopped Mazur Ali via TKO in the 5th round. Masternak improves his record to 14-0 (9 KOs)
On April 13, 2013, a 25-year-old Mateusz Masternak (29-0, 21 KOs) and Shawn Corbin met in the ring in a cruiserweight bout.
Masternak came in to the fight on a 29-fight win streak with a 72% KO rate, and was fighting after a gap of 3 months and 29 days.
Mateusz Masternak stopped Shawn Corbin via TKO in the 9th round. Masternak improves his record to 30-0 (22 KOs)
On December 19, 2009, a 22-year-old Mateusz Masternak (15-0, 10 KOs) and Jameson Bostic met in the ring in a cruiserweight bout.
Masternak came in to the fight on a 15-fight win streak with a 66% KO rate, and was fighting after a gap of 1 month and 25 days.
Mateusz Masternak stopped Jameson Bostic via RTD in the 7th round. Masternak improves his record to 16-0 (11 KOs)
On December 15, 2012, a 25-year-old Mateusz Masternak (28-0, 21 KOs) and Juho Haapoja met in the ring in a cruiserweight bout.
Masternak came in to the fight on a 28-fight win streak with a 75% KO rate, and was fighting after a gap of 3 months.
Mateusz Masternak defeated Juho Haapoja via unanimous decision in the 12-round cruiserweight fight. Masternak improves his record to 29-0
On May 30, 2021, a 34-year-old Mateusz Masternak (43-5, 29 KOs) and a 30-year-old fellow Polish boxer Adam Balski (15-0, 9 KOs) met in the ring in a cruiserweight bout.
Masternak came in to the fight on a 2-fight win streak with a 60% KO rate, and was fighting after a gap of 5 months and 18 days. Balski was on a 15-fight win streak with a 60% KO rate, and fighting after a layoff of 8 months and 11 days.
Mateusz Masternak defeated Adam Balski via unanimous decision in the 10-round cruiserweight fight. Masternak improves his record to 44-5, while Balski adds a loss to his record at 15-1.