This is a follow up of our previous paper -Trybu la and Zawisza [17], where we considered a modification of a monotone mean-variance functional in continuous time in stochastic factor model. In this article we address the problem of optimizing the mentioned functional in a market with a stochastic interest rate. We formulate it as a stochastic differential game problem and use Hamilton-Jacobi-Bellman-Isaacs equations to derive the optimal investment strategy and the value function.2010 Mathematics Subject Classification. 91G10; 91G30; 91A15; 93E20. Key words and phrases. Stochastic interest rate, stochastic control, stochastic games. J π,η (x, y, r, t) over a class of admissible strategies A x,y,r,t .As usually, the problem (2.3) might be considered as a zero-sum stochastic differential game problem. We are looking for a saddle point (π * , η * ) ∈ A x,y,r,t × M and a value function V (x, y, r, t) such that J π * ,η (x, y, r, t) J π * ,η * (x, y, r, t) J π,η * (x, y, r, t) and V (x, y, r, t) = J π * ,η * (x, y, r, t).