Chelsea hope to be in a position to rest Fernando Torres for Saturday's FA Cup third-round tie against Southampton by registering Demba Ba in time to play at St Mary's.
On Wednesday night, Newcastle boss Alan Pardew described Ba's move to Stamford Bridge as "done" after the Blues triggered the £7million release clause in the Senegal striker's contract.
There have been reports a three-and-a-half-year deal has been agreed and the striker is now undergoing a medical with Chelsea.
Ba's persistent knee problem could complicate things, though, and Blues interim manager Rafael Benitez has refused to speak about the 27-year-old.
However, Benitez has admitted the Blues must give Torres a break after blaming fatigue for the 1-0 Barclays Premier League defeat by QPR.
"Fernando is one of the players who needs to rest. Two or three players have been playing too many games in the last weeks and months," he said.
"Managing that was going well but against QPR it didn't work. Some of the players couldn't get to the level we were expecting.
"Without talking about names, if you have another striker you can play with two strikers if you need to. Or if you want to rest a striker then you can do that and at the moment we are a bit short."
Shaun Wright-Phillips hit his former club's faint title hopes by firing the second-half winner at Stamford Bridge.
Leaders Manchester United are 14 points ahead of fourth-placed Chelsea, who finally buckled beneath the heavy workload that accompanied their appearance at the Club World Cup in Japan last month.
Benitez conceded their chances over now overhauling United are bleak.
"I haven't been worried about the league table, I've just talked about one game at a time and now it's the same situation," the Spaniard said.
"If you can't win your games it will be more difficult but the priority is to think about the next game and give the players the confidence that we had before.
"We will analyse what went wrong and try to carry on with the things that we were doing really well.
"We have to do everything almost perfectly now if we want to reduce the gap. When you lose a game it's more difficult, but I can't be thinking about how many points we need."
Captain John Terry will soon begin warming-up with his team-mates as part of his rehabilitation from a knee injury, but the date for his comeback remains uncertain.
Goalkeeper Petr Cech is expected to be out for two to three weeks with his groin problem.