Essien had to be helped from the field shortly before the hour mark of the Blues' 3-0 derby win at Stamford Bridge after pulling up with what appeared to be a left knee injury.
That immediately caused concern, with the midfielder having missed significant parts of the past two seasons with cartilage and ligament problems in both knees.
Down but not out: Essien limped out of Saturday's win over West Ham
Manager Carlo Ancelotti attempted to play down fears of a recurrence of those issues after the game, describing the injury as 'muscle' related.
Scans today showed the problem actually was with a tendon but the 28-year-old escaped any serious damage and will be monitored ahead of Saturday evening's Spurs match.
Chelsea said in a statement on their official website: 'Michael had a minor problem with a tendon above his knee during the West Ham game and came off as a precaution.
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