Despite speculation that the rain might return, Hamilton was able to press on, and had 17 seconds on his pursuers by lap 29, half-distance, extending that gap, at times, by as much as a second a lap. Such was the pace now being set, that slicks soon came into the equation. Rain was still being reported as only a matter of minutes away, but the fine line between the choice of tyres was closer still.
In the end, Alonso and Renault - now with nothing to lose after dropping well out of contention - were the first to take the plunge. The Spaniard had been reticent to move to the grooved rubber, and his early laps on it appeared to confirm that reluctance, but soon the rest began to follow suit.
Webber, running fourth, was among the early adopters, when the move still appeared risky for the frontrunners but, when McLaren used Kovalainen as a guinea pig, it was clear that all were considering it, leaving just the question of when.
Massa seemed to be most in need, the Ferrari having dropped three seconds a lap off Hamilton's pace at times, but the Scuderia hesitated longer than almost everyone. Kubica stopped for his change on lap 53, along with the still impressive Sutil, while Hamilton was in next time around, his now 37-second advantage over Massa allowing the McLaren to rejoin still in front.
In the end, Ferrari didn't react for another couple of laps - enough time for Kovalainen to turn Jenson Button around at the chicane - and it proved costly for Massa, who had had his cushion over Kubica whittled away by the Pole, who gratefully accepted second on the road. Raikkonen, too, was late making the switch, but was able to resume in fifth, between Sutil and Webber, with 30 laps still remaining on the original race distance.
The wet start, however, meant that it was the clock that the teams needed to keep an eye on, but that attention would have been diverted by the sound of crunching metal and carbon fibre from behind the pits. Rosberg, having already required two new noses, gave the Williams team an even bigger repair job by comprehensively destroying his car against both sides of the Swimming Pool complex.
Fortunately, the rapid German was unhurt in the shunt, but the amount of debris required the safety car to make a re-appearance, eliminating Hamilton's 32-second lead at a stroke.
Just six cars remained on the same lap as the Briton at the point the race was neutralised, but the resumption would still provide controversy - and a degree of heartache. While the top three made it a clean getaway, no-one prepared to pull a risky move on the still damp surface off-line, the world champion - of all people - found himself caught out.
What followed capped a disappointing return to Monaco for the man who messed up in qualifying last year, but also spelt the end of the dream for Sutil and Force India. Raikkonen did not appear to be close enough to make a move on the German, or preparing to make one, but the Ferrari suddenly got into a tankslapper on the downhill exit from the tunnel and, even as Kimi fought to control the car, slammed into Sutil as the youngster prepared to turn in.
The damage was not enough to take either man out on the spot but, while Raikkonen was able to rejoin after another change of nose, there was no happy ending for Sutil who, having limped back to the pits, was told that suspension damage would end his afternoon. Unsurprisingly, the German was inconsolable, and not even the knowledge that Raikkonen would not score could soothe the hurt.