For those concerned about why Senna missed the match, it appears it was just fatigue. Without specifically saying Senna was tired, Pellegrini gave the following reason for his night off against United:
"There are a lot of games in the season and there will be consecutive weeks where we have a match every three or four days, so it was necessary to rotate the team. Senna, for example, is a player who will be going through a lot of wear and tear throughout the year."
So, it looks like he should be ready to go against a high-flying Numancia on Sunday. The match is not currently scheduled to air live on GolTV, but that changed halfway through last week, so it is still a possibility.