The 24-year-old Ivory Coast international arrived in the Midlands on Wednesday night and is on course to become the club’s first big money arrival of the summer.
Villa are expected to pay an initial £22million, with the fee potentially rising to near £30m depending on add-ons.
Guessand, who scored 12 goals in the French top flight last season and set-up eight more, is understood to have been on Villa’s radar for several months, with Unai Emery speaking personally to the player last weekend while convincing him to join.
Emery sees Guessand as a potential back-up to Ollie Watkins, while his ability to also play out wide and as a second striker was of particular appeal.
Guessand’s arrival could see another forward signing, teenager Zepiqueno Redmond, moved out on loan.
Villa, meanwhile, are braced for a possible approach from Newcastle for John McGinn.
The skipper is reported to be on the Magpies’ list of targets, with Eddie Howe keen to bolster his midfield options ahead of a Champions League campaign.
Villa rebuffed an approach from Everton for McGinn earlier in the summer and any move from Newcastle is likely to be met with a similar response, with Emery still viewing McGinn as an integral part of his plans.