In a surprise development in Chelsea's 1-0 win over Everton Saturday, Oscar was subbed out at the half in favor of Ramires. It turns out the Brazilian midfielder was dealing with an injury, as Jose Mourinho revealed in his postgame press conference.
From Chelsea's official Twitter account:
There will be some debate as to whether this was truly an injury or Oscar was simply not playing all that well due to fatigue. It was Mourinho himself who said Oscar was a bit worn down before the match, via Sky Sports:
Maybe in the last couple of matches he was not the same, because in the beginning of the season he was the best player in the team. He was the player that was really making the difference in the first three, four months of competition.
In this moment he's not being a match-winner, he's not scoring goals, but he's not playing bad. Not real problems. The talent is there all the time, but the physical top condition to express the quality he has is not always there.
We have to take care of him. He's a young boy. He's not a natural physically strong man, suffers with the accumulation of matches, suffers with the difficult weather we had.
Oscar is one of Chelsea's most important players—and presumably a huge reason why Mourinho felt confident he could sell a superstar like Juan Mata in January—so the hope will obviously be that his injury isn't serious.
As the Premier League title race heats up, Chelsea will need all hands on deck. Oscar is a huge factor in keeping Chelsea afloat atop the table.