Former World Champion Krzysztof Glowacki (27-1, 17 KOs) and fellow Polish star Mateusz Masternak (39-4, 26 KOs) have signed-up to act as reserves in the World Boxing Super Series cruiserweight quarter-finals. Assuming they are not needed to act as reserves, the fighters will box on the undercards of the quarter-final they are assigned to.

Glowacki is the reserve for the Mairis Briedis vs Mike Perez quarter-final and WBC world title match-up at the Riga Arena, Latvia on September 30. Masternak has been named as reserve for the Murat Gassiev vs Krzysztof Wlodarczyk quarter-final and IBF world title bout, date and venue to be announced.