Van Avermaet was able to cover attacks throughout the race, before riding to the finish with former team-mate Philippe Gilbert (Quick-Step Floors) and friend and training partner Oliver Naesen (Ag2r La Mondiale), edging out Gilbert in the sprint for the line.
While world champion and pre-race favourite Peter Sagan was not in contention after missing the move and then being caught in a crash, Van Avermaet said that he was confident that he could have beaten anyone at the end of such a hard race.
"I was confident sprinting against Gilbert, but you can never be completely sure in a sprint. You have to really back yourself and I did," Van Avermaet said.
"I know now that if things go right I can beat anyone, especially after such a hard race, but you have to be really focussed and make sure you get everything right."
Watch: Pro Bikes - Greg Van Avermaet's BMC Roadmachine
Team-mates at BMC between 2012 and 2016, Van Avermaet and Gilbert often found themselves targetting the same races, with Van Avermaet being unable to follow when his team-mate attacked.
However today was different, with Van Avermaet able to follow his fellow Belgian as Gilbert attacked a number of times in the final 20km, but was unable to shed either of his compatriots.
"We are the same type of rider and it wasn't always easy to get the right decisions when we were on the same team," Van Avermaet said.
"But for me Phil is still a big champion. Like you saw today he was always riding and always attacking; always giving 100 per cent effort.
"If he was in my team then I couldn't jump after him, but now I can."
Confidence high and with a team riding "much better than Milan-San Remo" where Van Avermaet was left poorly positioned at the bottom of the Poggio, the Belgian looks to be a real threat going into the Tour of Flanders on Sunday, April 2.
The BMC man has finished on the podium in two of the last three editions, and has also finished in the top ten on three more occasions, and now has his sights set on emulating a three-time winner of that race.
"I would love to become a well-known rider - a really big name - like Tom Boonen. If I do well then I hope that sort of attention will start to come.
"I've been fighting for 10 years to win E3 Harelbeke and now I've done it. I hope I can continue like this and my career can go on for a long time yet."
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Henry Robertshaw began his time at Cycling Weekly working with the tech team, writing reviews, buying guides and appearing in videos advising on how to dress for the seasons. He later moved over to the news team, where his work focused on the professional peloton as well as legislation and provision for cycling. He's since moved his career in a new direction, with a role at the Department for Environment, Food and Rural Affairs.
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