Manager Thomas Tuchel has admitted Chelsea still need more arrivals heading into the final few days of the transfer window.
Wesley Fofana is expected to complete a minimum £70 million ($82 million) transfer from Leicester to Chelsea, with the Frenchman having sat out the Blues' 2-1 win over the Foxes on Saturday.
Chelsea are still pushing hard to complete a deal to bring Pierre-Emerick Aubameyang to Stamford Bridge from Barcelona, while also pressing for Everton's Anthony Gordon.
The Blues are understood to consider Wilfried Zaha as a possible alternative to Aubameyang, with boss Tuchel still hoping to see more new faces arriving before the Thursday night deadline.
Chelsea's German coach has long since vowed to be happy with the squad at the window's close whatever the situation, but also admitted he hopes for further additions.
"Right now I think we could need some more players in some positions, but it's very close to the end of the transfer window and when September 1 comes, I will be a happy coach no matter what happens," said Tuchel.
"I will try to find solutions and not think about what might have happened or what could be.
"Everything that matters is reality and at the moment (against Leicester) what mattered was finding a way to win.
"What will matter at Southampton is the same, find a way to win, step up individually and push the team from my side. This is what we will do no matter if players will come or not."
Chelsea shook off Conor Gallagher's red card to defeat Leicester 2-1 at Stamford Bridge on Saturday.
Raheem Sterling's brace for his first goals for Chelsea dragged the 10-men hosts to the win, with club captain Cesar Azpilicueta stepping off the bench to make an important impact.
The Blues will head to Southampton on Tuesday with Gallagher suspended and N'Golo Kante still out with hamstring trouble, though Mateo Kovacic is building his fitness after a knee injury.
Spain defender Azpilicueta has found himself on the bench in the opening weeks of the campaign amid Chelsea's transforming squad.
Chelsea have already recruited Sterling, Kalidou Koulibaly and Marc Cucurella as new owners Todd Boehly and Behdad Eghbali make good on bold plans for spending and a squad revamp.
