Sheffield Wednesday handed the winger a deal at the club earlier this week after he managed to impress boss Darren Moore during training.
The 29-year-old adds to Moore’s options on the flanks as he continues efforts to bolster his squad in a season in which they are gunning for promotion.
Owls hitman Gregory has welcomed the addition of the former Middlesbrough man to the Hillsborough dressing room, and hailed him as a game-changer.
Gregory stressed that Mendez-Laing adds a lot of pace and physicality to Sheffield Wednesday and believes he is a great signing for the club.
“It is a big signing for us”, Gregory told a press conference while discussing the arrival of Mendez-Laing.
“He is a great player to have in the squad.
“Hopefully he can show what he can do this weekend.
“He is a game-changer.
“He is very direct, physical, strong and quick.
“He has got quite a lot going from him.
“It is difficult for the gaffer now because he has got some good players to pick from.”
Sheffield Wednesday are gearing up to host fellow promotion hopefuls Wycombe Wanderers at the weekend and Mendez-Laing could be handed his Owls debut.
