The two-time champion headed a thrilling Q3 session at two points, but was pipped on both occasions by Max Verstappen as the Red Bull driver's prowess in the final sector decided pole in his favour.
After his first flying lap in Q3, Alonso felt that he "drove like an animal" to briefly head the session, but had to dig deeper in his second run in his bid to overturn Verstappen.
He reckoned that his efforts were sometimes "over the limit" as he hoped to clinch an all-important pole at Monaco, but addressed the Aston Martin AMR23's weakness in the final part of the lap.
"We were increasing the level to an uncomfortable level of risk, let's say," Alonso reflected.
"I think both laps in Q3 were a little bit over the limit sometimes, but everything went fine. The last sector seems our weakest part of the circuit.
"We were, I think, eighth quickest in the last sector. So there is something going on there that we need to analyse a little bit. Maybe going Singapore or whatever is the next opportunity [to address] that."
Alonso explained that it was important to set out his stall early given the propensity for incidents on the Monte Carlo circuit, and was pleased to have achieved a front-row start despite Aston Martin's comparative deficit in qualifying relative to its race pace.
Source: Autosport