The club is set strengthen even further in readiness for the new premier league after agreeing a deal to sign Alvaro Negredo from Valencia CF.
The Spanish international, a member of their successful Euro 2012 squad, is set to join on a season-long loan once all the paperwork is complete.
The 30-year-old brings a wealth of experience, having scored 112 La Liga goals in 264 appearances, and has tasted Premier League football previously, with Manchester City.
He cost City £16.4m from Sevilla FC in the summer of 2013 and went on to score 23 goals in 48 appearances, including a Champions League hat-trick.
Negredo has linked up with Karanka's squad in Marbella.