The Belgian joined a move on the penultimate lap and although the course favoured the purest of climbers, the Classics and one-day specialist hung on over the ascents. He and Jakob Fuglsang (Denmark) caught lone leader Rafal Majka (Poland) inside the final three kilometres after the Pole saw his original breakaway companions – Vincenzo Nibali and Sergio Henao – crash on the final descent.
In the sprint for the line, Van Avermaet simply had too much for Fuglsang with Majka taking bronze.
"It ran perfectly in the end, I had the legs that I needed. It was a hectic finale but in the end everything went well," a jubilant Van Avermaet told Het Nieuwsblad at the finish.
For the majority of his career, Van Avermaet, 31, had the tag of one of cycling's nearly men. That impression started to turn last year when he won a stage of the Tour de France.
This year, he has been in fine fettle, winning Het Volk, the overall in Tirreno, and picking up another Tour stage win and a stint in the yellow jersey. His Olympic Games win, however, eclipsed all of that. He survived the crashes on the final descent, kept his head, and powered to the win with an unmatchable sprint.
"There were so many down, and then I began to look around. I didn't take too many risks on the downhill, which was better.
"This is a very nice moment. I've quite often been close, just not won, but this makes up for it."