Chelsea were made to pay for their lack of proficiency in front of goal and will now have to come from behind if they are to reach the Carabao Cup final after a 1-0 defeat to Middlesbrough at the Riverside stadium.
Hayden Hackney with the all-important goal for the Championship side in a battling performance and they held on to what is now a priceless win going into the second leg in a fortnight in west London.
For large parts of the game, Michael Carrick was the happier manager, getting the shape of his team right and forcing Chelsea to do things they would normally not want to do.
Levi Colwill a centre-back forced into playing at left back was pinned into mistakes and Moises Caicedo, expensively bought to motor up this team lost his man as Middlesbrough academy product Hackney benefited with a simple tap-in for the goal.
This Chelsea team is a work in progress, they have their moments but at this stage in the game, it was the Championship side who were dominating and the fury in manager Pochettino's eyes was crystal clear before he introduced Armando Broja and Mykhailo Mudryk to try and turn the tide of the game.
Chelsea were wasteful, exemplified by Cole Palmer's hat-trick of misses but credit to Boro who simply defended brilliantly until the end. This is only the first half and Chelsea will try and turn it around but from a rainy Riverside Stadium, this is how we rated the Chelsea players out there.
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.