But he has vowed that if their defence of the Champions League crown ends in Spain on Tuesday, Chelsea will go down fighting.
Karim Benzema’s hat-trick in the first leg of their quarter-final at Stamford Bridge last week means Chelsea face an uphill task but Tuchel has urged them to show their true selves after he was disappointed with their first-leg display as he dreamed of a wonderful story.
Chelsea got a 1-1 draw away at Real in last season’s semi-final but Tuchel feels the task is both different and tougher now.
“It was at the training ground, at the youth stadium, and it is one of the biggest challenges to perform as an away team in the Bernabeu,” he said. “It is even more difficult if you need to win by a minimum of two goals, maybe with a three-goal difference. It makes it almost impossible but it is worth trying. We need to overperform.
“We do not have the biggest chance given the first game’s result and given the competition and the opponent and the stadium we play in but we never manage our effort and belief by the chances we have of a result.
"We never did and we will not start [now] by giving less because it is very unlikely we will make it. We need nothing else than a fantastic script if we are to overcome this but it is always allowed to dream.”
Tuchel hopes that if Chelsea do bow out, it is in the manner of champions. He told them to fight to the last, explaining: “By not accepting it before it ends and by leaving everything on the pitch and by showing that we can work harder, that we can play better, that we can take more risks and show our true face and live up to our true potential and then we accept what comes next.”
He lamented a lack of intensity last week, while also blaming the Premier League for not allowing him to make five substitutions a game to keep players fresher.
“We face a huge disadvantage in terms of physicality,” he said. “Real plays a whole year with five changes and we play in the most demanding league and the most matches. We need the physicality to be a special team.”
Chelsea will be without the injured Romelu Lukaku, who has an achilles problem, but captain Cesar Azpilicueta, who missed the 6-0 win at Southampton because of coronavirus, is back.
It is a return to Madrid for Mateo Kovacic, who won the Champions League three times as a Real squad player, and a reunion with Luka Modric. His fellow Croatian was first his hero and then someone he became close to.
“I admired him as a child he played for my favourite club Dinamo Zagreb and now he is my friend I admire him even more,” he said. “Great player, great person.”
Modric turns 37 in September but Kovacic believes he can carry on into his forties. “He was always as good as he is now,” he said. “I know him for the last five, six or seven years and he is on the same level, which is amazing. I still see him playing three or four more years on this level.”
Kovacic took inspiration from past comebacks, when Real overturned a 2-0 first-leg deficit against Wolfsburg in the 2016 quarter-finals and when Chelsea lost 3-1 to Napoli in 2012 but also went on to win the Champions League. “Football is always surprising but we need to be ready 100 percent to do a comeback,” he said.