Leclerc was just under two tenths faster than Hamilton in the day’s second session with Fernando Alonso a surprise third quickest.
However, not everyone showed their hands, with Oscar Piastri not competing a qualifying simulation, explaining why he was down the order.
A threat of rain made for a busy start to Free Practice 2 with the skies notably duller than they’d been earlier in the day.
That saw all cars out early though not all to the same programme.
Verstappen was on a set of hard tyres while team-mate Sergio Perez was on mediums for Red Bull Racing – the pair had only run the medium tyres in the opening hour earlier.
Piastri and Daniel Ricciardo also had the hard tyres fitted.
Most were on the medium rubber, including Leclerc who went fastest at 14 minutes with a 1:12.260s, quicker than Hamilton had managed as he topped the opening practice hour.
The Ferrari driver kept getting faster, lowering the benchmark time to 1:12.125s, still on the medium rubber.
He was still on the yellow-walled rubber when he dipped into the 1:11.573s bracket, before swapping onto the softs to log a 1:11.278s.
Set with 27 minutes complete in the session, it left him 0.535s ahead of Verstappen.
In the pits, Piastri reported tagging the barrier as he sat 11th, though there was no obvious damage to his MCL38, and he was sent back on his way.
Verstappen also had a moment as the rear stepped out of line exiting Portier and whacked the armco barrier.
With his qualifying simulation, Alonso rose to second ahead of Hamilton, Lando Norris, and Lance Stroll.
The Spaniard then slipped back a spot when Hamilton completed his single lap run, the seven-time champion banking a 1:11.466s.
Alonso had been baulked by traffic, which was proving an issue for most every driver around the short Monaco circuit – Yuki Tsunoda and Verstappen also tripped over each other through the Swiming Pool.
With 10 minutes remaining, Piastri was only 12th fastest, the McLaren driver had not completed a soft tyre run.
He sat 1.088s away from Leclerc’s best, and 0.4s away from team-mate Norris, who had completed a qualifying simulation, and was fifth fastest.
Indeed, Piastri ended the session without a short run, suggesting he had far more pace in hand than 12th in the standings would suggest.
Meanwhile, Leclerc topping the session underscored the promise Ferrari has this weekend, while second-best for Hamilton suggested Mercedes could spring a surprise in qualifying.
Alonso was half a step further back 0.4s away from Leclerc, while Verstappen ended the session on a set of hards, having used softs and mediums earlier on.
The Dutchman was only fourth best, at 0.535s away from the outright pace.
However, there were clearly different programmes and priorities, making the finishing order of the session not representative of where every team stands.
Ferrari and Mercedes look promising, with Red Bull Racing something like it had been in Imola – thereabouts, but without the blistering pace advantage it once enjoyed.
Where McLaren fits in is also unclear given its programme, while Aston Martin surprised with Stroll nipping at Carlos Sainz’s heels.
Daniel Ricciardo ended the day with the 16th best time, a 1:12.577s, just two-tenths down on Tsunoda who was 12th.
It was a compact field with the top 10 cars covered by less than a second, while from Alonso in third to Pierre Gasly in 17th were also covered by less than a second.
A final hour of practice remains, beginning at 12:30 local time on Saturday (20:30 AEST) ahead of qualifying at 16:00 (midnight AEST).