Alongside Real Madrid, Hoffenheim are the only other club still unbeaten in Europe's main leagues.
Alongside Real Madrid, Hoffenheim are the only other club still unbeaten in Europe's main leagues and are fourth in Germany's top flight, but just a point ahead of six-placed Dortmund.
There's plenty at stake at Sinsheim's Rhein Neckar Arena where a win will lift either team to third behind leaders Bayern Munich and RB Leipzig, who both have 33 points.
At 29, Nagelsmann is the youngest coach in the Bundesliga's history.
He took charge in February, helping Hoffenheim avoid relegation by finishing 15th last season, but this campaign they are the only team yet to taste defeat in their first 14 German league games.
They even took a shock lead at Bayern last month before earning a 1-1 draw at the Allianz Arena.
A knee injury cut short his career at the age of 20, but Nagelsmann learnt the coaching trade under Tuchel, who mentored him while working with Augsburg's youth teams, and he hopes to get one over his former mentor.
"His work is, of course, exceptionally good," said Nagelsmann.
"But I pay next to no attention to what he does, because I don't know his work in detail and we also have a few good ideas.
"There's never been a game where beforehand I've thought that I'd settle for a draw.
"That's the same this time around.
"Of course, it's great that we're still unbeaten, but the desire to stay unbeaten is always there, because we always want to win."
Tuchel's Dortmund have been erratic of late.
They lost 2-1 at Eintracht Frankfurt in late November, before hammering Borussia Moenchengladbach 4-1 and drawing 2-2 at Real Madrid, but then needed a 90th-minute Marco Reus goal to draw 1-1 at Cologne last Saturday.
Raphael Guerreiro, Mario Goetze and Shinji Kagawa are all set to return for Dortmund after knocks.
Portugal international Guerreiro has been absent with a leg injury since the 5-2 win against Hamburg on November 5.
Nagelsmann is waiting on the fitness of Kerem Demirbay, Kevin Vogt and Germany international Sebastian Rudy.
Tuchel's Dortmund is buoyed by Reus, who has been superb since his return from injury three weeks ago, with four goals and six assists in his five games back, alongside Pierre-Emerick Aubameyang, the league's top scorer.
"It should be a really good game, Dortmund will try to dictate the pace," said Nagelsmann.
"Their attack is really quick - that's one of Dortmund's strengths - and we'll need to keep it in check."