Chelsea head coach Antonio Conte will continue with his 3-4-3 formation, which could be ominous for captain John Terry.
After three successive Premier League wins with nine goals scored without reply, Chelsea lost 2-1 in the EFL Cup at West Ham on Wednesday.
Terry was making his first appearance in more than six weeks following an ankle injury and in a three-man defence which has been alien to him for much of his career.
The defender appeared rusty, was beaten in the air by Cheikhou Kouyate and was switched from the central position to the left of the three-man defence at half-time.
Chelsea play at Southampton on Sunday, with Conte poised to continue with his favoured system and Terry facing a likely return to the bench.
Conte said: "I don't like to talk about individual players. We win together and we lose together in every circumstance.
"It's logical that John came back from injury and it's not easy to restart and to find quickly the right shape. I'm satisfied (with) him, (with) the team.
"John is an important player for us, if he plays, if he doesn't play, for the changing room, for his team-mates, for the club.
"I repeat: in this case always it's important the team and not to think or to speak about an individual player.
"I have always to take the best decision for the team, never for an individual player."
For so long Terry has been an integral figure in Chelsea's numerous successes.
And he issued a reminder on Friday, the 18th anniversary of his Chelsea first-team debut. He has since made more than 700 appearances.
The 35-year-old wrote on Instagram: "On this day 28/10/1998 I made my debut for @chelseafc.
"Dreams can come true and don't ever let anyone tell you otherwise."
Conte made seven changes from last Sunday's 4-0 win over Manchester United for the loss at West Ham which ended Chelsea's League Cup participation and means the Blues have just two competitions remaining this term: the Premier League and FA Cup.
He wants a response against Southampton but has no intention of tinkering with his tactical formation.
Conte added: "We wanted to win and to continue in the cup. It didn't happen.
"It's a pity, but on Sunday we have another tough game and it's important our head now stays concentrated for this game.
"It's not a win or a defeat can change the idea, my idea or the confidence of the players.
"After two defeats, against Arsenal and Liverpool, in the future (we would say) 'we never must play with 4-3-3 or 4-2-3-1' if it's only the problem for the system.
"No, I think it's the right way for the players. It's a good fit for the team, this system.
"I think we found a good balance and also we have a good offensive situation, because in every game we scored a goal.
"For sure we must continue to work in the offensive situations and also in defensive situation.
"It's not easy, it's completely different when you defend with four and when you defend with three defenders.
"I think a lot of positive things and we want to continue in this aspect. We are working very hard to improve. We understood that this way is the right way."
Chelsea enter this weekend's fixtures in fourth place, one point behind Manchester City, who lead Arsenal and Liverpool on goal difference, after playing nine of the season's 38 games.
Former Juventus and Italy head coach Conte has not set a target for the campaign.
"We shouldn't look at the table," he added.
"It's important to improve game by game, to continue to trust in the work. These are the most important things now, not the table.
"In this league, there is great balance and in every game, anything can happen. You can win, but you can lose."