Max Verstappen and Sergio Perez led the field for Red Bull in Saturday's final practice in Monaco, the pair just edging Aston Martin's Lance Stroll.
The Canadian clocked in just 0.166s behind Verstappen, while Ferrari' Carlos Sainz and McLaren's Lando Norris rounded off the top five.
With minutes to spare, the session was brought to a premature end when Lewis Hamilton hit the outside barrier at Mirabeau and damaged the left front corner of his Mercedes.
Conditions were perfect along the sunny shores of the Mediterranean ahead of the weekend's final practice, with air temperatures at 26.5°C and the track sitting at a toasty 43.9°C.
Drivers will have been reminded by their teams of the importance of steering clear of trouble in the session as any mishap could compromise their presence in qualifying later in the day.
Minutes after the track went green Alpine's Esteban Ocon was seen nursing his car out of the tunnel and back to the pits after his A523 was hit with an apparent power unit issue.
Running at the outset on the soft compound tyre, Perez set an early benchmark, the Red Bull charger just edging Sainz and Aston Martin's Lance Stroll.
But all three were overhauled in short order by McLaren's Lando Norris. Stroll then popped to the top before Perez recouped the lead.
Fifteen minutes into the session, there was still no sign of a Mercedes black arrow out on track. But it was Verstappen's time to vault to the top on his first flyer with a 1m13.794s that was a comfortable 0.583s clear of Perez.
But as the track continued to rubber in, permutations were fast and furious among the front-runners, with Alonso and then Perez picking up the lead baton, albeit only briefly as Verstappen again bumped everyone down a spot.
Meanwhile, almost halfway through the session, Hamilton and Russell finally took to the track, both running at a conservative pace.
Relentless, Verstappen continued to lower his own benchmarks, the Dutchman dipping into the 1m12s. While circulating among the top four, Leclerc urged his team over the radio to 'lift' his SF-23 to avoid his car bottoming into the Swimming Pool complex.
As Mercedes' drivers upped the pace, Hamilton moved up to fifth while Russell, running seventh, admitted to a "hefty hit of the wall" in the final sector that encouraged him to return to the pits for a check-up.
With 20 minutes to go, most of the field regrouped which led to a lull in the track action. As the track filled up once again, with qualifying simulations in order, Valtteri Bottas slotted in among the top ten.
As traffic swelled, so did the number of white flags warning drivers of the presence of a slower car ahead.
But Haas' Kevin Magnussen – who recovered after running down the escape road at Ste Devote – stopped entirely just before Portier, the Dane obeying an urgent order from his crew over the radio.
The Virtual Safety Car was activated to allow for a the Haas to be safely evacuated.
Proceedings went green with 6 minutes left on the clock, but almost immediately Hamilton clouted the barrier at Mirabeau. Damage to the front right of the Mercedes was light but the Briton was unable to reverse and bring his car back to the pits. .
The mishap brought out the red flag and predictably brought the session to a premature end.
There was little complaining in the Red Bull camp, with Verstappen and Perez sitting atop the timesheet, with Stroll concluding his practice in third place.
Sainz and Norris completed the top five, with Gasly, Leclerc, Hamilton, Ocon and Bottas completing the top ten.
Russell was just outside the first half, but Alonso lingered in P14. However, barring any unforeseen issue on the Spaniard's Aston Martin, he'll be a force to be reckoned with in qualifying.