Madrid can extend their advantage when they host Real Sociedad on Saturday at the Santiago Bernabeu after being gifted another opportunity to strengthen their already-commanding position in the Spanish title race.
Sevilla were boosted by a 2-1 victory over third-placed Real Betis last weekend but failed to follow up that victory against a determined Alaves side, who edge up to 18th in the table.
Five draws in seven La Liga games for Sevilla have even given their rivals hope of finishing second, with fourth-placed Barcelona 10 points behind but with two games in hand. Betis, in third, are nine points back, having played one game fewer.
"We weren't at our level today," said Sevilla defender Nemanja Gudelj. "We have to keep fighting. We had chances in the second half but it wouldn't go in."
Alaves had chances of their own to seal victory, with Sevilla goalkeeper Bono called upon to deny Luis Rioja's powerful shot in the first half.
But Sevilla had the best opening and it came late, Jules Kounde squaring to Munir El Haddadi six yards out only for the forward to fluff the finish, allowing Alaves to claim a deserved point.
la liga real Madrid sevilla Deportivo Alaves