Diego Simeone says he worries about "everything offensively and defensively" and admitted Atletico Madrid need to improve after seeing their 100 per cent start in LaLiga ended by Real Sociedad.

Atletico entered Saturday's contest, the first competitive fixture played at Sociedad's Reale Arena, having won their opening three league matches.

However, a fired-up Sociedad took all three points thanks to a deflected opener from Martin Odegaard and a debut goal for former Arsenal defender Nacho Monreal.

Atletico coach Simeone concedes there is work for his side to do.

"Everything worries me, I worry about anything that happens offensively and defensively," he said.

"We need to grow. We know what we have and what we are and where we need to go. LaLiga is very difficult, when you don't start a match how you should start, you lose.

"Since pre-season this is the first defeat, we need to improve and grow."

Simeone added that Atletico did not produce their best football until the game was already gone.

"The team wore its best face when already 2-0 [down]," he said. "In the final part [of the game] it's when we identified more with what we were doing."