Chelsea finished top of their group to reach the knockout stages, but have pulled the short straw by drawing Atletico after the LaLiga leaders finished runners-up to Bayern Munich in their group.
Atletico are among the favourites to win the competition this season, with a mean defence, a tight, creative midfield and an in-form Luis Suarez leading the attack.
While Simeone will be looking to go all the way this year, Tuchel has European pedigree having led PSG to last season’s final – and the German coach knows he is under pressure to make his mark given the ruthless way in which predecessor Frank Lampard lost his job.
Follow all the action on our live Champions League match blog.
Big Hudson-Odoi decision
Callum Hudson-Odoi suffered the ignominy of being a sub who was subbed at the weekend – but he starts tonight.
Here the BT Sport team discuss Thomas Tuchel’s decision, and how the winger will respond…
James Robson | Chelsea correspondent
That Chelsea bench must be one of the most expensive in history – if not the most expensive.
Inside Chelsea’s dressing room
Here’s a peek inside the Blues’ changing room – as you can see, they’ll be wearing their lighter change strip tonight.
Chelsea arrive in Bucharest
Here are Chelsea arriving in Bucharest earlier this evening…
As for Atletico, there are few surprises as Luis Suarez and Joao Felix lead the attack.
So, Olivier Giroud leads the line for Chelsea this evening, with Timo Werner and Callum Hudson-Odoi in support.
Behind them, Mason Mount, Mateo Kovacic and Jorginho form a midfield three, with no room for N’Golo Kante yet again.
A back four of Cesar Azpilicueta, Andreas Christensen, Antonio Rudiger and Marcos Alonso sits in front of goalkeeper Edouard Mendy.
Atletico Madrid team news
Atletico XI: Oblak; Llorente, Savic, Felipe, Hermoso; Correa, Koke, Saul, Lemar; Joao Felix, Luis Suarez
Subs: Grbic, San Roman, Kondogbia, Torreira, Renen Lodi, Dembele, Vitolo, Camello, Garcia, Sanchez
Chelsea team news
Chelsea XI: Mendy; Azpilicueta, Christensen, Rudiger, Alonso; Mount, Jorginho, Kovacic; Hudson-Odoi, Giroud, Werner
Subs: Kepa, Caballero, Kante, Abraham, Pulisic, Zouma, Chilwell, Ziyech, Gilmour, James, Havertz, Emerson
So, given it’s a European night, we should get team news at any point from 6:30pm GMT onwards – so watch this space…
Atletico face ‘home’ test away from Madrid
Atletico are in unfamiliar surroundings despite this being a home tie, with the fixture to go ahead at the Arena Nationala in Budapest, Hungary following Spanish government restrictions on travellers entering the country from England.
But Simone insisted: “We don’t have to talk about things we cannot manage. This is what we are living today.
“There are a lot of difficulties for many people, many hard workers and we just love football so this is what we have to do. This is where we have to play and we just have to concentrate on the game that we have here.”