After conceding first in their previous three LaLiga games, Real Betis were looking to turn the tables and created two big chances in the opening three minutes.
Diego Llorente’s goal-bound header was acrobatically cleared off the line by Raphinha before Abde Ezzalzouli raced past the Barcelona defence but was denied after going one-on-one with Inaki Pena.
An end-to-end opening spell also saw LaLiga’s leading scorers go close, as Lamine Yamal beat his marker and fired towards goal from a tight angle, only to be denied by Rui Silva.
Even if the pace stayed consistent, the early scares for both sides saw the defences eventually get on top, leading to more ambitious attempts with Dani Olmo unleashing a 25-yard shot that sailed over the crossbar.
But as the contest was edging towards a goalless first half, Barcelona carved through Los Verdiblancos’ defence with a flowing passing move, completed by Jules Koundé’s cross for Robert Lewandowski to tap in his sixth LaLiga opener this season.
A Betis side unbeaten in five at home wasn’t going to submit easily though and the hosts nearly levelled through Sergi Altimira’s header, which went just wide of the post.
Los Verdiblancos continued to create opportunities and Ezzalzouli was next to threaten the Barca goal, but his powerful strike couldn’t beat Pena.
However, Betis’ pressure eventually paid off when Frenkie de Jong fouled Barcelona loanee Vitor Roque inside the area. Referee Alejandro Muñiz Ruiz pointed to the spot and Giovani Lo Celso held his nerve to convert, firing high past Pena.
With a provisional seven-point title race lead at stake, the Blaugrana rallied late, and Yamal’s defence-splitting through ball found Ferran Torres, who fired under Silva to seemingly secure all three points.
Barca looked in cruise control as they were heading towards a first win in three LaLiga games, but Diao had different ideas as he flicked Aitor Ruibal’s cross towards goal and past a rooted Pena.
While their wait to beat Barcelona goes on, Betis’ home form remains a huge positive, as they are now unbeaten in six matches and remain just three points off LaLiga’s European spots.
As for Barca, their winless run extended to four league games, and Hansi Flick’s side missed out on the chance to extend their LaLiga lead over fierce rivals Real Madrid, who now have two games in hand – two victories from which would see them overtake their sworn enemies at the summit.