Knowing only a win would do at the Camp Nou, the defending La Liga champions conceded an injury-time equaliser when Angel Lafita headed home in second-half stoppage time, effectively ending Barcelona's title challenge.
The Catalans, already out of the Champions League and Copa Del Rey, have only won one trophy this season and Busquets conceded his side's league fate is now all but sealed.
"I guess the Liga is over for us now," he told reporters after the match.
"We should learn from this for the future."
Barcelona captain Xavi shared a similar sentiment, insisting it is time for his side to look ahead to next season.
"We feel bad," the 34-year-old said.
"We didn't live up to the expectations this season.
"We have to be self-critical and start all over next season."
Barcelona face an away trip to Elche before hosting Atletico Madrid to draw their season to a close with the latter set to win the league if they prevail in their next two matches.
