In testing conditions - a world away from those in which Molinari recorded an eight under par 63, one outside the course record.
That third round had taken the Italian into a one stroke lead over Northern Ireland's Darren Clarke.
Shots were dropped like confetti in the morning, but the weather had thankfully improved by the time Molinari and Clarke teed off - although both bogeyed the 455 yard second to slip back to 14 under and 13 under respectively.
It needed only one more hole for Clarke to go from one behind to four back.
Like Peter Hedblom in the group ahead he found the water right of the green and had two unsuccessful attempts to splash it out.
A double bogey seven went on his card whereas Molinari came out of a bunker to within four feet and birdied.
Clarke's deficit became five when he three-putted the short fifth, but Molinari did the same on the next.
They were 14 under and ten under, while England's Graeme Storm, who could deny Clarke a spot in The Open Championship, was up to third on eight under.