Davis and Danns had to be substituted with injuries during the opening 20 minutes of the goalless draw at Cardiff on Tuesday night.
Centre-half Davis has a back problem and midfielder Danns damaged medial ligaments.
Last season's top scorer Darren Ambrose is close to fitness after six weeks out with a bruised leg and could make a timely return, with Danns set for a spell on the sidelines.
Palace's injury problems do not end there with Anthony Gardner (ankle) and Adam Barrett (foot) doubtful and David Wright (calf), Lee Hills and Sean Scannell (both knee) still missing.
And on-loan Everton striker James Vaughan serves the second game of his three-match ban.
Neil Warnock could name an unchanged side when he takes QPR to his old club.
Rangers are still without right-back Bradley Orr (calf), centre-back Fitz Hall (hamstring), midfielder Alejandro Faurlin (groin) and striker Rob Hulse (Achilles), but Warnock is hopeful all four will be available after the forthcoming international break.
Warnock may therefore stick with the line-up which was held 0-0 by Millwall on Tuesday night.
Defender Peter Ramage and winger Lee Cook are long-term absentees with knee injuries.
Club captain Martin Rowlands has been an unused substitute for the past three games after 11 months out with a cruciate injury and will be hoping to get onto the pitch.
Striker Jamie Mackie continues in attack before joining up with the Scotland squad for the first time while Shaun Derry and Clint Hill line up against their former club.
Source: DSG
Source: DSG