Controlling crystallization and glass-forming tendencies of molecular liquids is of great scientific and practical importance. In the present work, we show that a lot can be learned regarding this process by introducing temperature and pressure as thermodynamic control variables. For the glass-forming liquid ketoprofen and its non-hydrogen bonded analogue, we have investigated changes in the crystallization rate along different isolines located in the two-dimensional T–p phase space. This has included isobaric (p = const), isothermal (T = const), and isochronal (τα = const) data. Our results reveal that the crystallization tendency of the investigated liquids can be tuned by moving along specific thermodynamic pathways. In particular, we highlight that among considered isolines the overall crystallization rate is the least affected by the density increase for the isochronal (T, p) state points. Interestingly, for various thermodynamic conditions with the same τα the estimated value of the thermodynamic driving force toward crystallization Δμ was found to be almost constant.