A measurement of angular correlations in Drell-Yan lepton pairs via the ϕ∗ observable is presented. This variable probes the same physics as the Z/γ∗ boson transverse momentum with a better experimental resolution. The Z/γ∗→ee and Z/γ∗→μμ decays produced in proton--proton collisions at a centre-of-mass energy of √s=7TeV are used. Normalised differential cross sections as a function of ϕ∗ are measured separately for electron and muon decay channels. The cross-section is also measured double differentially as a function of ϕ∗ for three independent bins of the Z boson rapidity.