Levante's Nabil El Zhar slotted home a rebound after 30 minutes but with Barca carrying a greater attacking threat after the break they equalised through an own-goal by Juanfran.
Messi set up all three goals for Tello and Barca will take a comfortable lead back to the Nou Camp.
Messi reached another landmark in his illustrious career with his 400th match in a Barcelona shirt having made his official debut in October 2004 against Espanyol.
Earlier, Mikel Gonzalez scored twice and Carlos Vela grabbed the other in a 3-1 victory for Real Sociedad in their first leg against Racing Santander, whose goal came from Mahamadou Kone.
Real Madrid have a 1-0 advantage over Espanyol from their game on Tuesday and holders Atletico Madrid play Athletic Bilbao on Thursday.