Luis Suarez and Lionel Messi scored in two minutes as Barcelona broke 10-man Atletico Madrid to go 11 points clear of their La Liga title rivals.
Diego Costa was sent off in the 28th minute at Nou Camp for insulting referee Gil Manzano. Atletico held on for almost hour, but Suarez and Messi struck late for a 2-0 win. That left Barca almost out of sight with seven games to play and maintains momentum for this week's trip to Manchester United in the Champions League quarter-finals.
"We're a little closer," coach Ernesto Valverde said.
Suarez added: "We've taken two steps forward."
United coach Ole Gunnar Solskjaer watched the deadly duo deliver.
Costa's dismissal followed coach Diego Simeone saying a win was the only result to keep Atletico's challenge alive.