Real Madrid could see its Spanish league lead reduced after being held to a 1-1 draw at Rayo Vallecano on Sunday.
Joselu put Madrid ahead only three minutes into the match against its southern Madrid rival, but the hosts equalized through Raúl de Tomás in the 27th.
The draw moved Madrid six points clear of second-place Girona, which visits fifth-place Athletic Bilbao on Monday.
Third-place Barcelona, which won 2-1 at Celta Vigo on Saturday with a stoppage-time penalty kick converted by Robert Lewandowski, was eight points behind Madrid. Fourth-place Atletico Madrid, which routed Las Palmas 5-0 at home Saturday, was 11 points off the lead.
It was a disappointing result for Madrid against a Rayo team that had lost three consecutive league matches and hasn't won in seven straight.
Real Madrid remains unbeaten in its last 19 league games, with 14 wins and five draws. It failed to score only once, in a 0-0 draw against Rayo in November.