Alaphilippe is a two time world champion who enjoyed a tilt at the Tour de France title in 2019.
"Julian called me this week to tell me he was leaving." Lefevere told Belgian daily Het Nieuwsblad.
"He'd been thinking about it at night for weeks and it had been making him sick, but he told be he's leaving the team," said Lefevere.
Alaphilippe was the star rider at the Belgian team for some years but with the arrival at the top of local rider Belgium's Remco Evenepoel he would no longer be the team's chief priority.
