Alaves failed to make the most of their chances as Atletico Madrid left Mendizorroza with a goalless draw.
The hosts should have taken the lead on the half-hour, but Brazilian forward Deyverson somehow headed over from point-blank range after Victor Laguardia had hooked the ball onto the crossbar.
Atletico could have scored a late goal when Nicolas Gaitan raced clean through, but goalkeeper Fernando Pacheco dived in to take the ball off his feet.
At the other end, defender Theo Hernandez, on loan at Alaves from Atletico, then forced a fine save from Miguel Moya before tempers boiled over following the final whistle.
Atletico Madrid captain Diego Godin and Deyverson appeared to spit at each other when players from both sides squared up.
Diego Simeone's Atletico are in fourth but lost the chance to close up on the leaders, and will now regroup for next week's Copa del Rey semi-final against Barcelona, when Alaves will tackle Celta Vigo.
Saturday's early kick-off saw Villarreal win for the first time in six matches as they beat Granada 2-0 at El Madrigal, with goals from Bruno Soriano and Alvaro Gonzalez.