Arsenal and Chelsea are reportedly keeping tabs on the Portugal Under-23 star this season.
TheMirror claim the Premier League clubs sent scouts to watch Costa in action on Saturday as Wolves beat Rotherham 1-0, where they saw him miss a first-half penalty.
And now bookmakers Ladbrokes have responded by making Arsenal 2/1 favourites to sign the 23-year-old when the transfer window reopens this summer.
Chelsea trail in the market, with the Premier League leaders priced at 3/1 to complete the potentially big-money move.
A Ladbrokes spokesman said: “He may be set to Costa lot for any potential buyer.
“But Arsenal look favourites to stump up the cash and secure the Portuguese ace’s signature.”
Costa initially joined Wolves on a season-long loan from Benfica in the summer and earned a £13million permanent move to Molineux in January.
He’s bagged 10 goals and provided seven assists so far this season and is said to have caught Arsenal and Chelsea’s interest after his performance in the shock FA Cup win over Liverpool.
