Yobo suffered a head injury during the draw with Wolves while Pienaar is recovering from a knee problem that has caused him to miss the last three games. Osman did not travel because of an ankle injury.
Lucas Neill and John Heitinga are ineligible while club captain Phil Neville and defender Phil Jagielka, both sidelined through injury, have travelled to Lisbon to support the side.
Everton (from): Howard, Hibbert, Distin, Gosling, Baines, Coleman, Rodwell, Bilyaletdinov, Cahill, Jo, Saha, Yakubu, Fellaini, Nash, Wallace, Duffy, Akpan.
