The first 2^+ excited state in the neutron-rich tin isotope ^{136}Sn has been identified at 682(13) keV by measuring γ -rays in coincidence with the one proton removal channel from ^{137}Sb. This value is higher than those known for heavier even-even N=86 isotones, indicating the Z=50 shell closure. It compares well to the first 2^+ excited state of the lighter tin isotope ^{134}Sn, which may suggest that the seniority scheme also holds for ^{136}Sn. Our result confirms the trend of lower 2^+ excitation energies of even-even tin isotopes beyond N=82 compared to the known values in between the two doubly magic nuclei ^{100}Sn and ^{132}Sn.