Diego Costa was sidelined from the squad in Chelsea's Premier League encounter with Crystal Palace.
Costa had come back from a relatively busy time out with his national side Spain scoring against Luxembourg, where he put an end to an alarming goal-scoring drought for his adopted country.
However, in the process the Spaniard seemed to sustain a thigh injury which Mourinho claims will see him out for up to a month.
Some may see this though as a little bit of an exaggeration by Mourinho of his current fitness so that he may restCosta for Champions League action in midweek, ahead of a big game against a somewhat reformed Manchester United side.
Costa absence doesn't stop Chelsea edging Palace
Whichever the circumstance, Chelsea certainly didn't lack any of Costa's firepower in their 2-1 win over Crystal Palace. With Oscar and Fabregas scoring two fine goals to seize yet another 3 points and put them 5 points clear at the top.
Whilst fitness set-backs for Costa will be worrying for Chelsea fans as consistency will prove vital for their title campaigns, the lack of match fitness for the goal machine may indeed prove his mortality.
As the season drags out Mourinho then will have to of course balance the fitness of his players with consistency and this week it certainly seems as if the boss has balanced Costa's fitness nicely, something that will seem vital as the season plays out.