Chelsea are on the brink of completing a reported £63m deal for the Spaniard.
The 24-year-old looked to be on his way to Manchester City earlier this window but Pep Guardiola’s Premier League champions bid £30m and then refused to meet Albion’s valuation of £50m.
The deal will make Cucurella the seventh most expensive defender in the history of football.
Cucurella made 35 appearances for the Seagulls last season, following his £15m move from Getafe, and was named Brighton’s player of the season.
Speaking at the Blues pre-match press conference, Tuchel said: “Well it [the Cucurella transfer]’s not done yet, but I don’t want to tell you that I don’t know anything about it of course.
“The paperwork is in process and hopefully we can get it finished before noon and that Marc is our player.
“And then if it goes through it opens up some options, like for Levi Colwill to maybe find some more game time elsewhere.
“Marc is a fantastic player, a young player, he’s hungry, mobile and very intelligent. He can play in several positions in our system and that’s why we hope the transfer goes through.
“Hopefully when things go through, Marc is the option [at left-back] but I think he can play very well in the back three. So he’s a bit like the profile of [César] Azpilicueta, but with a left foot, and he gives us many options.”
Chelsea academy star Colwill is expected to join Albion, either on loan or permanently, as part of the Cucurella deal.
Speaking on the teenage defender’s impending departure, Tuchel added: “It’s a bit hard to judge him, he came back, there was not a lot of game time in pre-season to give to him because of a little injury he caught in training.
“So the situation is the situation, for the moment it is very individual always. If there is a possibility for him to have a good loan or a situation where he can develop and improve, then we are open for any talks and any solutions.