And while Rush is back ahead of schedule, there is also returns from injury for Richie Rees and Deiniol Jones.
The Blues have made a stuttering start in the Magners League but coach Dai Young insists they are determined to bounce back from last week's 28-20 defeat at Munster.
Young said: "That was probably the best we've played all season. If we play like that week-in, week-out we'll win a lot more than we lose.
"All we can do now is build on the performance at Musgrave Park for the visit of Connacht to the Arms Park."
Wales prop Gethin Jenkins misses out with a neck injury and joins Tom James, Martyn Williams, Rhys Williams and Sam Warburton on the sidelines.
The Blues will defend an unbeaten record at the Arms Park which stretches back to January while Connacht have not won in Cardiff since 2001.
Blues: Leigh Halfpenny; Richard Mustoe, Jamie Robinson, Jamie Roberts, Gareth Thomas; Ceri Sweeney, Jason Spice; John Yapp, T Rhys Thomas, Gary Powell, Deiniol Jones, Paul Tito (capt), Maama Molitika, Andy Powell, Robin Sowden-Taylor.
Replacements: Taufa'ao Filise, Rhys Williams, Scott Morgan, Xavier Rush, Richie Rees, Nicky Robinson, Tom Shanklin.
Connacht: F Carr; A Wynne, J Hearty, M Deane, M Roberts; A Dunne, F Murphy; J Lyne, A Flavin, R Morris; A Browne, M Swift; J Muldoon (C), J O'Connor, C Rigney.
Replacements: S Cronin, R Loughney, A Farley, M McCarthy, K Campbell, I Keatley, L Bibo.
Referee: Carlo Damasco (Italy)