Pitch is being relaid and there's some construction going on, so they're also playing the Copa Diego Armando Maradona (effectively the League Cup) games there. Not sure when there'll be back at the Monumental. Seems to have gone very quiet there, actually. But you'd assume they'd be back in time for the regular League season.
Either way, I didn't watch the game but Palmeiras apparently ran rampant and you'd expect them to finish the job back in Sao Paulo.