Highlights Celta Vigo 2-0 Atletico Madrid September 02 2018
Atleti, who are being tipped by many for a strong title challenge, had Stefan Savic dismissed for two yellows.
“I’m not worried about the result,” said Simeone.
“I’m calmer than ever, because this is a wake-up call for us. We didn’t play well and Celta were lethal.”
Atletico, champions in 2013-2014 and runners-up last season, have four points from three games going into the international break.