The LHC is producing top quark pairs in abundance. This allows to study the top quark with very high precision. Measurements of differential cross sections in exclusive region of additional jets by the ATLAS experiment are presented. Measuring differential cross sections as a function of the number of jets enables a stronger constraint on MC generators and let us probe the top pair production in a region of phase space much closer to the one relevant for ttH measurement and searches. While theory predictions are available at NNLO QCD and NLO EW for inclusive top-quark pair production and NLO QCD and NLO EW for the production of a ttbar pair in association with a jet, subleading orders play a role. The results here presented are performed as a function of variables particularly sensitive to radiation or other effects correlated with the number of jets. The agreement with Monte Carlo generators will be discussed as well as the state of the art of the new theoretical predictions.