The team now aims to keep Masson busy fighting, in the hope it would further lift him in the rankings.
In addition to the bout this month, Masson is hoping to fight in October and November.
Masson said he was looking forward to the Grewal fight, saying he appreciated the opportunity to gain more experience against southpaw fighters.
Two world champions in the cruiser-weight division, IBF World Champion Jai Opetaia and unified WBA and WBO world champion Gilberto Ramirez, are southpaws.
Also, David Nyika, whom Masson hopes to fight eventually, likes to switch between an orthodox and southpaw stance.
Meanwhile, Grewal has a decent record of 7 - 2 - 0, however, all of his wins were against either debut boxers or boxers with fewer than three professional fights to their name.
Grewal has some experience fighting in Australia, where he took on two-time world title challenger Mark Flanagan and New Zealand-born Ricky Esilva, losing to both of them.
Floyd Masson vs Dharmender Grewal will take place on the Liam Paro vs David Papot world title eliminator undercard at Pat Rafter Arena, Brisbane, Australia on September 18.
The fight is unlikely to be televised in New Zealand.
Benjamin Watt is a retired boxing judge and New Zealand boxing writer with a decade of experience. Watt has also been BoxRec’s New Zealand record-keeper since 2014.