Luck will miss his second straight game with a lacerated kidney and partially torn abdominal muscle. Castonzo will miss his first game since 2011 with a sprained right medial collateral ligament.
Pro Bowl safety Mike Adams (ankle) is doubtful, while cornerback Greg Toler (groin) and outside linebacker Erik Walden (heel) are listed as questionable after doing limited work in Friday's practice.
Inside linebackers Jerrell Freeman (ribs), D'Qwell Jackson (hamstring) and Sio Moore (back), cornerbacks Vontae Davis (hamstring) and D'Joun Smith (knee) and running back Frank Gore (ankle) are all listed as probable.
Indy (5-5) hosts Tampa Bay (5-5).
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