Questions over the future of Antoine Griezmann will now likely intensify, with the France international reportedly close to joining Barcelona, but Simeone is not concerned about losing any of his key men in January.
"On the contrary," he told reporters when asked if certain players will attempt to force an exit. "I think this could be a new challenge. Everything that is bad, we make it into a positive. I wouldn't say it was a failure, because we knew this could happen.
"I think a failure is when you have an objective and you don't reach it, and we knew this could happen, so it is not a failure for us. I think the team has shown that we never give up, and we have a long season ahead, we will see what happens at the end of the season.
"It doesn't hurt, because this is football. We've managed to get more points from the team which finished top of the group than the team which finished bottom. It is difficult to explain, but from now on we are just going to concentrate on what is coming, whether it be the Europa League, Copa del Rey or La Liga.
"Football is like this, it doesn't depend on tactics, possession and stats, at the end of the day what is important is to be decisive, and you need to score. But in my opinion the team is well, we have only lost one game and it was in the last minute, but no excuses. We need to carry on with the season and be valued at the end of the season."
Atletico reached the final of the Champions League in 2014 and 2016, losing to city rivals Real Madrid on both occasions.