An analysis is presented based on an integrated luminosity of 2.9 1/pb of 7 TeV center-of-mass energy proton-proton collision data in ATLAS at the Large Hadron Collider. The data have been collected between March and September of 2010. Clear signals from W+jets and Z+jets events have been obtained. The aim of the analysis is to observe top quark pair production in proton-proton collisions. The dominant background contributions in the signal region are W+jets and multijet production processes. The rates of these backgrounds in the signal region have been estimated by data-driven...