Chelsea will travel to the Riverside Stadium without a dozen of their first team players with Mauricio Pochettino confirming Christopher Nkunku picked up a hip injury in training and won't be involved.
The former RB Leipzig forward now joins the likes of Ben Chilwell, Reece James, Carney Chukwuemeka and Benoit Badiashile on the treatment table.
On Nkunku, Pochettino said ahead of the game tomorrow night: "I think we'll have the same squad for the semi-final - nothing new. Christopher Nkunku's injury? It's not related to his old injury. It's a different problem - an issue in his hip. He won't be involved tomorrow; we will see if he is available for Saturday. We have to be cautious. I hope it is not a long period, but at the moment he is not training and he is recovering. But it's not a big issue."
Middlesbrough manager Michael Carrick was a young player at West Ham when Boro, the club he had joined on schoolboy terms as a nine-year-old, won the League Cup to claim the first major trophy in their history in 2004.
Boro are huge underdogs in this with Chelsea winning their last three games and looking like they are just beginning to pick form. But the history of this competition is that of the ultimate outsider upsetting the odds, so expect Chelsea boss Pochettino to go with his best team and try to create a mountain for Boro to struggle with in the second leg at Stamford Bridge.
Now with everything that has been said ahead of the game, this is how we expect the Blues to line up:
1. Dorde Petrovic- 5
Didn't have to make a lot significant save in the first half and the conceded.
2. Axel Disasi -5
The Chelsea man bailed out Colwill in the first half. Didn't do much wrong all game.
3. Malo Gusto -5
Looked assured and sharper with his passing. Didn't join the attack as much as he would have liked.
4. Thiago Silva- 7
Exquisite defending for most of the game. Not at fault for the Middlesbrough goal.