We study aspects of the TT deformation of 2d Yang-Mills theory on a Riemann surface, introduced by Conti, Iannella, Negro and Tateo. We focus mainly on the large N behavior of the partition function of the theory on the two-sphere, showing that the Douglas-Kazakov phase transition persists for a range of values of the deformation parameter, and that the critical area is lowered. The transition is still of third order and also induced by instantons, whose contributions we characterize. Joint work with Leonardo Santilli, and work in progress.