Manuel Pellegrini has a lot of work to do at the London Stadium this summer, if he is to guide his West Ham side back into contention for the Europa League places, after their miserable campaign last term.
Defence seems to be a department where the Chilean is desperate to bolster.
And if West Ham manage to bring both defenders to east London this summer, it could turn out to be a double deal that signals the start of what is a very bright future for the club.
Following James Collins' release from the club, concerns regarding Winston Reid's fitness and Angelo Ogbonna on the wrong side of 30, an injection of youth into the Hammers' defence will surely be a priority for Pellegrini.
Gibson, 25, and Mawson, 24, would both fit that criteria, and for a combined fee of around £40 million, West Ham's defence could be totally transformed next season.
The Middlesbrough man is a solid defender. He's strong in the air, as well as being quick along the ground, and he has a lot to offer at the very highest level.
The Swansea centre-back, meanwhile, is equally as competent as his Championship counterpart.
He is a competent man-marker, and would bring a certain level of tenacity to the Hammers' back-line.
West Ham's recent recruitment has been woefully poor, but if they manage to sign the English duo, Hammers fans will finally have something to shout about.