The Swansea striker replaces David Villa, who suffered an ankle injury during Atletico Madrid's game against Celta Vigo in the Primera Division on Sunday.
Michu, who has scored 27 goals since arriving in south Wales from Rayo Vallecano just over a year ago, was preferred to more established names such as Fernando Llorente and Tottenham's Roberto Soldado.
And the 27-year-old will now come into contention for an international debut against either Belarus or Georgia.
Spain lead Group I on goal difference from France but have two remaining qualifiers to their rivals' one.
Four points from Friday's Palma meeting with Belarus and Georgia's visit to Albacete on Tuesday would guarantee top spot and a place in next summer's finals.