A measurement is presented of the (formula presented) inclusive production cross section in pp collisions at a center-of-mass energy of (formula presented) using data collected by the ATLAS detector at the CERN Large Hadron pffiffi Collider. The measurement was performed in the lepton + jets final state using a data set corresponding to an integrated luminosity of 20.3 fb-1. The cross section was obtained using a likelihood discriminant fit and b-jet identification was used to improve the signal-to-background ratio. The inclusive tt production cross section was measured to be (formula presented) pb assuming a top-quark mass of 172.5 GeV, in good agreement with the theoretical prediction of (formula presented) pb. The (formula presented) production cross section in the fiducial region determined by the detector acceptance is also reported.