Midfielder posts recovery news on Twitter
The South-African midfielder had to be substituted in last weekend's 0-0 draw against Wigan, after a tweak to his groin, which David Moyes said worsened the team's performance.
A scan on Thursday revealed that the damage is not as bad as first thought, but is severe enough to see him sit out of the game at Eastlands.
Pienaar wrote on his Twitter page: "Scan results weren't that bad but it looks like I'll need a week of recovery."
Everton will be looking to extend their fantastic run against City, where they haven't lost since 2007. But they will face Roberto Mancini's men without both Pienaar and Mikel Arteta, with the Spaniard serving the final game of this three-match suspension.