Humans are able to modify the spontaneous pace of their actions to facilitate interactions with their environment. This ability relies upon high-level cognitive functions (e.g., motor inhibition) but there is a dearth of knowledge regarding the brain areas that underlie such temporal control. A limiting factor is that current neuroimaging techniques (e.g., EEG, *f*MRI) are extremely sensitive to movement, which inhibits the monitoring of brain activations during motor tasks. Over the last decade, functional near-infrared spectroscopy (*f*NIRS) – a non-invasive imaging method – has been widely adopted for experimental motor paradigms given its tolerance for motion artefacts. In the present investigation, we used a continuous-wave *f*NIRS system to record prefrontal and motor haemodynamic responses among 16 participants who performed a spatial-tapping task that varied in terms of motor complexity and its tempo, which was externally determined. To discriminate between physiological noise and meaningful cerebral signals, the physiological data (i.e., heart and respiratory rates) were recorded so that frequency bands of such signals could be regressed from the *f*NIRS data. Particular attention was taken to control the precise position of the optodes in reference to the cranio-cerebral correlates of the NIR channels. The results show greater oxygenation over the motor cortex in a fast vs. slow trials. Moreover, greater oxygenation was observed over the prefrontal cortex when producing actions at medium vs. fast tempi. Collectively, the present findings suggest that frontal cognitive processes serve a critical role in the modulation of motor pacing.