Chelsea lost the encounter 1-0 at Goodison Park with Richarlison scoring the only goal of the game right after half time.
The Blues remain in third place but their lead over fourth-placed Arsenal has been cut to only three points with four games remaining.
Just like in recent weeks, individual errors cost Chelsea points in this game, leaving Tuchel concerned about his side's chances of finishing in the top four.
“Of course, it was always like this," he told reporters when asked if they now face a battle to qualify for the Champions League.
"I said it many weeks ago that I didn't ever feel safe. We are never safe. By the way, if we are in a race for top one, top two, or top four, no matter what the race, the last four games to only have four points will never be enough, no matter which race we are in.
"We have to take care of ourselves. At the moment we don't get the points when we play well and deserve more and we lose when we play okay, this is a bad mixture."
"What can I do? The ball is free, then give a goal away. It is the worst thing that can happen to you in this atmosphere and situation. It happens too often, we struggle to play without big mistakes. That's why we struggle to have results.
"If there is something I can do I will try it but if I knew about it I would have done it before. I think, for me, the key is to have a clean sheet. Manchester United was a different game, more open, fluid, more spaces, and we finally scored late and conceded straight away.
"For me, this is more like the game against West Ham. The opponent defends deep, we struggle to find space in the first half, but against West Ham we had a clean sheet and played without any big mistakes.
"That gives us the chance to score late. If you run behind against an opponent like this, in this atmosphere and install emotion and belief in a stadium like this and the opponent's team, you struggle."
