The two-time Giro d’Italia champion succumbed to injuries suffered in a fall during the second stage and abandoned about 100km into Friday’s hilly stage to Sisteron.
Team doctors said x-rays revealed no broken bones, but that Basso couldn’t handle the increasing pain as the race unfolded.
“Ivan bit the bullet as long as he could, but today the situation was too much,” said Liquigas sport director Mario Scirea. “The group went at ‘full bloc’ right from the start and, seeing him in difficulty, it was better for him to stop.”
Basso will return to Italy to completely recover and then the team will consider whether he needs to make changes to his race schedule.
Basso’s main goal for the season is to try to win the Giro for a third time.
Other big names to pull out of Paris-Nice include Andy Schleck (RadioShack-Nissan-Trek), Nick Nuyen (Saxo Bank), Taylor Phinney (BMC), Bauke Mollema (Rabobank) and first-day leader Gustav Larsson (Vacansoleil).