Influential Boro captain Howson missed the weekend draw with Rotherham United due to a knock, while wingman Jones came off with a hamstring issue against the Millers.

One player definitely out is striker Emmanuel Latte Lath, who injured a hamstring early on in the first instalment versus the Blues on Teesside.

Boro won 1-0 and are bidding to become the first EFL side to reach the League Cup final at Wembley since Bradford City in 2013.

Middlesbrough boss Michael Carrick. Picture: PA Wire.

Boss Michael Carrick said: "We're still waiting to see on Jonny (Howson) and Izzy (Jones).

"Manu (Latte-Lath) is out a little bit longer. You won't see him for a little bit more time.

"We're still assessing Jonny and Izzy, trying to give him as long as we can to maybe be ready and in and around the squad.

"The squad is feeling good, preparation has been short.

"We're in the rhythm of training and playing games. It's business as usual in terms of rest and recovering and preparing and getting the balance right.

"As a group, the boys are hugely looking forward to the game. It's a great challenge for us to embrace and take on."

It's also business as usual in terms of Aston Villa target Morgan Rogers, who is likely to again be involved for Boro at Stamford Bridge, despite ongoing speculation over his future.

Halesowen-born Rogers, top-scorer in the Carabao Cup this season with four goals, has the subject of two failed bids from top-flight outfit Villa, with Boro sticking to their guns and not currently entertaining the prospect of business regarding a player who they only bought for £1m from Manchester City last summer.

City have a significant sell-on clause regarding Rogers.

Carrick added: "Whether there is interest in the players or not is irrelevant really. If there is, fine.

"But it doesn’t affect what I do and what the players do. It’s always just about preparing for the next game.

"If that interest is there, then it does show that we’ve got good players. That’s natural.

"If you’ve got good players, other teams might look. We do it to other teams and it’s how the game works really."

Middlesbrough FC boss gives updates on key duo ahead of Chelsea trip and why he's relaxed over interest from Aston Villa in star