Chelsea announced on Friday that the club has completed the signing of striker Demba Ba from Newcastle, just a few days after the Blues sold striker Daniel Sturridge to Liverpool.
Ba joins Chelsea on a 3 1/2-year contract after the Blues triggered a release clause of just over $11 million.
The 27-year-old will be eligible to feature in Chelsea's FA Cup third-round match at Southampton on Saturday.
"It feels good to be here, I'm very happy and very proud," Ba told Chelsea's website. "When the club who won the Champions League wants you, the decision is very easy. This club is massive and that's something that helped the decision a lot. It was not a hard one.
"It was important for me, and for Newcastle, to get my future sorted and now we can move on. Now they have the whole month to buy someone and for me as well, the sooner the better. Now I am here I just need to get settled in."
A Senegal international, Ba is tied for third in the Premiership with 13 goals in 20 appearances this season for the Magpies, who sit only two points above the drop zone.
Ba's addition gives Chelsea another option up top alongside Fernando Torres, who has netted seven goals in 20 matches this term.