Luis Suarez opened the scoring against his former club in the 26th minute against a Liverpool side that spurned a couple of good chances to equalize during a strong spell after the halftime break. Messi then quashed the comeback effort when he doubled the lead from a rebound with 15 minutes left and followed that up by making it 600 career goals for Barcelona by curling in a perfectly struck free kick in the 82nd.
Liverpool dominated long stretches of the match but failed to finish its chances when it had the hosts on their back foot, especially early in the second half. Mohamed Salah still almost grabbed a valuable away goal for Liverpool late when he hit the post.
Coached by Ernesto Valverde, Barcelona is aiming to replicate the treble of titles it achieved in 2009 under Pep Guardiola and 2015 under Luis Enrique. It clinched the Spanish league title last weekend and plays Valencia in the Copa del Rey final on May 25.
Liverpool is trying to reach consecutive Champions League finals after losing last season 3-1 to Real Madrid.
Barcelona extended its unbeaten streak at home in Europe's elite club competition to 32 straight matches, a run that started in 2013.
The return leg at Anfield is next Tuesday.
