This is very true.
How the media builds up the game pre-match, how the press plays up
the results, whatever is reported in the newspapers and television
programmes do have an impact on the psychology of the teams and
players involved.
Sometimes, it can be difficult to accept a defeat after going 40
games without one. We all saw what happened to the once
"invincible" Arsenal team. Their form collapsed after their
unbeaten run, 9 more than Chelsea, was ended, ironically at Old
Trafford.
Of course, no teams are alike, and Chelsea could very well bounce
back the following week against Newcastle. Afterall, we are talking
about a multi million dollar team of talents. 
It will be interesting to see how Chelsea recovers from this
defeat.