Diego Simeone has urged Atletico Madrid to quickly switch focus to their Champions League clash with Real Madrid, having boosted their title hopes with Saturday's win over Athletic Bilbao.

Julian Alvarez came off the bench to score Atletico's goal as they edged out Athletic 1-0, taking advantage of Real Madrid's 2-1 defeat at Real Betis to go top of LaLiga.

Barcelona could leapfrog them when they host Real Sociedad on Sunday, but the two results provided a major boost to Simeone's hopes of capturing his third Spanish title.

But Atletico face their cross-city rivals in the first leg of a Champions League last-16 tie on Tuesday, and Simeone has warned they cannot afford to get complacent before that game.

"We have a big game in the Champions League and at the moment we just have to focus on that and get well rested during these three days off," Simeone told reporters.

"What we have to do at the moment is continue to strengthen the collective work of the players and not lose that focus."

Simeone also hailed Alvarez, who sealed the victory just seven minutes after coming on for Alexander Sorloth.

Atleti's 16 goals scored by substitutes in LaLiga this season are more than any other team in Europe's top five leagues, with Lazio second with 14 in Serie A.

"Today we faced a very difficult opponent. They defended well and had some good chances with Nico and Inaki Williams. We were lucky to have Julian in the second half and for him to finish the counterattack the way he did," he said.

The manager added that he was thrilled to have his compatriot, who arrived from Manchester City in pre-season.

"Sometimes players come in, they are special and as a coach you know that. They are different and, well, I like their modesty and I love their versatility," he said.