The Slovakian of team Tinkoff attacked on the Kemmelberg, rode clear with three others and sprinted ahead for victory. He took his second Ghent-Wevelgem title after 2013.
"Why would I panic?" Sagan said of his many second places. "In life there's more important things thing victories or second places. I'm riding for passion, not for ambition."
Sagan dedicated the win to his father-in-law, who he said "had a hard time yesterday" without wanting to add anymore information.
With his win, Sagan became the first world champion to win Ghent-Wevelgem since Rick Van Looy in 1962.
"Cycling's like that," added Sagan. "The jersey or not, I'm happy to win this race."
The race appeared to be slipping out of Sagan's hands when it split early into the 242km race.
He rode alone in a big group of favourites. LottoNL-Jumbo pulled for Sep Vanmarcke and worked with Tinkoff to bring the groups together. On the second climb up the Kemmelberg, Sagan attacked and pulled away Fabian Cancellara (Trek-Segafredo). Vanmarcke joined them and they caught lone leader Viacheslav Kuznetsov (Katusha).
Watch: Sagan 'bluffed' his way to Ghent-Wevelgem win
Sagan said that his team erred in the first part of the race, but corrected itself for the win. He added that today he made sure he rode intelligently so that he would not lose out as he did on Friday in the E3 Harelbeke. Two days ago, he escaped with Team Sky's Michal Kwiatkowski and lost in the final sprint.
"It was a little bit different today. What do you want to hear? I think everyone knows I was tired. Yeah. I worked a lot Friday and then in the final, I was like how I was. There's not too much story about it," Sagan explained.
"Today, Vanmarcke was pulling, but he stopped, but cycling is like that. I said I won't make the same mistake as before and pull to the finish. We had a good gap to the group. The guy from Katusha began early and I said, 'I have to go behind him,' and he pulled me a very good sprint."
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