Chelsea assistant coach Steve Holland rued injuries to Marco Van Ginkel and Ramires in their 2-0 win over Swindon Town in the English League Cup.
Both Van Ginkel and Ramires are in doubt for Saturday's crunch English Premier League derby with Tottenham at White Hart Lane.
"(The result was) not perfect because we have got an injury to Marco, which is a little bit early to be certain but it doesn't look good," Holland said.
"He will have a scan tomorrow on an injury to his knee and of course his substitute Ramires also had to go off with a muscular injury at the top of his hip in the glut (gluteal) area which was causing him more discomfort as he tried to run it off.
"He will be a major doubt for Saturday... not out for sure yet but a major doubt for the Tottenham game at the weekend."
Juan Mata has been the name on everyone's lips at Stamford Bridge, with manager Jose Mourinho rarely playing the Spanish attacking midfielder.
In Mata's two Premier League appearances this season, he has been subbed off after just 57 and 65 minutes respectively, causing speculation Mourinho does not have the 25-year-old in his grand plans.
Holland defended Mourinho's treatment of the Spaniard, claiming the Portuguese boss is simply sending a message to his all-star line-up that no-one is protected.
"Obviously a lot has been made of the Mata situation, he is a high profile player," Holland said.
"The message to all our attacking players from Jose Mourinho from day one has been they need to contribute offensively in terms of their production not just look a good player but score goals, make chances and be a threat to the opposition goal and of course they have to contribute and defend."
Holland said the packed fixture schedule was beneficial to Chelsea's chances of claiming silverware in the latter half of the season.
"We have four chances (to win a trophy) and we have a squad of 20 outfield players where there is really not a great deal in between the majority of the players," the assistant coach said.
"At this stage of the season it is important we are playing twice a week to give regular games to all of the squad.
"That might change towards the end of the season when you are looking to rest the players.
"But at this stage it is good to have the regular fixtures and it is an opportunity to win a trophy in February/March, it certainly is the first one anyway so that is the target."