Actually, I neither question his injury, nor his decision to play MC.
On a side note, folks might recall he had very quick victories against
Albert Montanes (45 mins), an old dirt baller and PCB (don't remember exact time,
probably little under or over an hour), a new dirtballer. In fact, somebody even
commented that Novak plays this well with an injury.
Actually, in retrospect, Novak played that well not despite the injury but
due to the injury. Instead of playing his usual basline game with extended
rallies, he was coming to the net quite often and was basically trying to
finish the points quicker. I believe the reason he was playing in that manner
was to deliberately get out of the court quickly. It worked, until he
had to play GGL who was in form, having just won Casablanca.
Also, Novak openly told that he deliberately did not withdraw or
retire from semifinal as "people will talk about it".
As all of us know now, he gave it a try and once he lost the 1st set,
he essentially did a tank job to get out with dignity.