Fermilab-Tevatron. Measurement of the TOP TOPBAR production cross section in PBAR P collisions at a centre-of-mass energy of 1.96 TeV in the lepton + jets channel. Two complementary methods are used which discriminate between signal and background, b-tagging and a kinematic likelihood discriminant. The data sample has an integrated luminosity of 0.9 FB-1. The average of the two methods is given here at an assumed top quark mass of 175 GeV as well as at the world average of 172.6 GeV.