Luis Suarez opened the scoring in the 16th minute after Lionel Messi played him through with a defence splitting pass and the Uruguayan rounded goalkeeper Marko Dmitrovic and tapped into an open net, 0-1.
In the 66th minute, Eibar were reduced to 10 men as Fabian Orellana was shown his second yellow card.
With 15 games remaining in the season, Barcelona have a commanding seven-point lead over Atletico Madrid in the Liga table.
Barcelona has a Champions League with Chelsea on the horizon, but first it must tend of business in La Liga when it travels to Eibar on Saturday.
In Serie A they'll be hoping to get a sense of normality back and after winning their last eight in succession in the division, Juve will be confident of keeping the pressure firmly on Napoli at the summit.
Philippe Coutinho entered the match for Andres Iniesta in the 63rd minute, but Eibar's courageous performance was killed by their own hand in the 66th.
The match threatened to spiral out of control when Eibar manager Jose Luis Mendilibar was sent to the stands for protesting a similar situation - Sergio Busquets kicked the ball away during a stoppage of play but escaped a booking. Will they be able to take home the three points even if they rest some of their key players?
It was something of a exhausted display by Barca at Ipurua, perhaps unsurprising given that the Catalans have been in action twice a week for the most part in 2018 due to their games in La Liga and their run to the final of the Copa del Rey.
That was the 14th time the Argentine had hit the woodwork this term in the Primera Division and his performance deserved a goal. They can not, however, allow a shift in focus to the European stage to come at the cost of throwing away a healthy lead in the league.
"We are only thinking about the game in Ipurua".
It is a remarkable turnaround from their dismal form at the start of the season when they lost seven of their first 11 games, although coach Jose Luis Mendilibar said his side had barely altered their style, which is based on pressing high, no-nonsense defending and frequent crosses into the opposing box. Tuesday's match against Chelsea will provide Barcelona with a real marker of how well they compare to the club's previous great sides.
Deportivo La Coruna suffered a second straight defeat under Clarence Seedorf, the Dutch coach's side losing 1-0 at Alaves to a scorching strike from former Barcelona loanee Munir El Haddadi. However, they will take on a hard opponent since they will play against FC Barcelona this Saturday.