"This means that we are doing things well," said Sociedad goal-scorer Mikel Merino. "Each time we don't take the full three points we are disappointed. But seeing us up there at the top gives us confidence."
Merino put the hosts in front in the 63rd minute when the midfielder headed in Adnan Januzaj's corner. But substitute striker Youssef En-Nesyri outjumped his marker to head in Roque Mesa's pass to level for Leganés in the 78th.
Leganés goalkeeper Iván Cuéllar earlier saved shots from Merino and Januzaj with the score still 0-0. It was the first match for Leganés under new coach Javier Aguirre and the team had a good performance in defending against one of the best attacks in the league.
Leganés stayed in last place. The modest Madrid-based club has lost nine of 13 matches. Barcelona hosts Celta Vigo on Saturday, when Real Madrid visits Eibar. Barcelona and Madrid will play their delayed "clásico" match on Dec. 18.
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