Newly-appointed Bayern Munich coach Thomas Tuchel oversees his first training session at German first division Bundesliga football club FC Bayern Munich on March 28, 2023 in Munich, southern Germany. AFP
"My week was 'work, eat, sleep, repeat'," said the manager, who was appointed after the surprise sacking of Julian Nagelsmann.
"We need to make it work, no matter how much time there is."
Bayern host Dortmund with the visitors one point clear at the top of the Bundesliga table, ahead of a German Cup meeting with Freiburg and a Champions League quarter-final clash with Manchester City.
"April and May are very important for clubs like Bayern, who define themselves through titles."
It will be a reunion of sorts for Tuchel who spent two years in charge at Dortmund, taking over when Jurgen Klopp left in 2015.
Tuchel, however, said he would not use his sacking by Dortmund in 2017 as motivation for this weekend.
"It's been six years" Tuchel said. "When I played in Dortmund with Paris, I was hugged by a lot of people.
"A lot of people, including me, regretted that my time came to an end (at Dortmund) but it's way too long ago to hold grudges."
Tuchel admitted he had little time to determine a starting XI, saying "it's going to be a very unfair line-up tomorrow because I have to rely on my first impressions."
The manager said he "tried not to overload the players after a turbulent week", saying "less is more".
Tuchel told the press conference his firing from Chelsea "still hurts", saying he missed the "extraordinary bonds" he had with many at the club.
"I was no longer a part of this group, where it felt like a family. But now I have a new challenge."
Dortmund come into the match having won nine of their 10 league matches in 2023, with Bayern winning just five in the same period.
"It's a big match, a huge challenge for us to step up against a team on a run like that, but it brings out the best in us."
Tuchel said forward Jamal Musiala was in line to return from a thigh injury which saw him miss Germany's friendlies, but a decision would be made on Saturday morning.
Earlier on Friday, Dortmund manager Edin Terzic said Tuchel's appointment "obviously changed our preparation a little bit" for the top-of-the-table clash.
"We don't know how much Thomas Tuchel will continue on with what Julian Nagelsmann did in the last few weeks, or whether he brings in completely new ideas.
"But what hasn't changed is that they still have a top manager on the bench and a top team on the field."
Terzic admitted his side had watched "the first six games of Thomas Tuchel at Chelsea" to get an idea of "what could happen in this situation or that".
The Dortmund coach praised Tuchel's ability to "bring Chelsea together in just a few months and be rewarded by winning the Champions League at the end of the season".
"He's one of the best managers in Europe and one of the most successful."
Terzic spoke publicly for the first time on Nagelsmann's sacking, saying "I find it to be a real pity what happened with Julian Nagelsmann, who's an absolute top coach."
"But we know how quick things can go in football."
Dortmund have not won in Munich in the league since 2014 but Terzic said "we're a different side" this year.
Terzic said on Friday several players would return from injury for the clash, including goalkeeper Gregor Kobel, midfielder Julian Brandt and forwards Youssoufa Moukoko and Karim Adeyemi.
Terzic confirmed that there were "question marks" over English teenager Jamie Bynoe-Gittens and Germany defender Nico Schlotterbeck for the game, while USA forward Gio Reyna and Belgium defender Thomas Meunier have been ruled out.
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