The Lotto Soudal rider was the last survivor of an early six-man which included second placed Maximilian Schachmann (BORA-hansgrohe), a long way back at 2min 38sec and Grega Bole (Bahrain-Merida), third at 2min 42sec.
“I absolutely wanted to be in the breakaway today to aim for the stage win," de Gendt said. "I tried to take the mountains jersey as well, but I did not want to waste too much energy on this. T
"he peloton quickly brought down our bonus to two minutes, but I did not panic. The hardest part was yet to come, being a short and steep hill. I was riding at a very high pace there, hoping the strongest would survive, but only Luis Maté (Cofidis) was able to follow.
"However, he could not take the lead anymore and he just stayed in my wheel until the next hill, the Coll Formic. Because I knew Maté really was at his limit, I attacked again and he had to let go.”
De Gendt now leads the overall, points and mountains classifications at the end of the 163.7km stage from and to Calella.
“On the first day, there is no GC leader yet, so then it is difficult to find a team willing to lead the chase," de Gendt said. "For the sprinters, it was a bit too tough today and I responded well to that. On top of that, I think the GC riders will not care too much about me.
"The two uphill finishes could make me lose fifteen minutes, so it does not really matter that I am two minutes ahead now. Tomorrow I should keep the leader’s jersey, but I suppose I will not be able to follow the top riders on the next day.”
It was a quiet day for the overall favourites including Chris Froome (Sky), Mitchelton-Scott's Simon and Adam Yates and Richie Porte (Trek-Segafredo) who finished in the main group.
Stage 2 is a relatively flat 166km from Mataro to Sant Feliu de Guixols with a bunch sprint expected.