Chelsea coach Carlo Ancelotti has described Frank Lampard as the world's best midfielder.
"His two goals (against Birmingham) showed he is the best running midfielder in the world. He has this fantastic quality to time his runs into the box,” The Sun quoted Ancelotti, as saying.
Florent Malouda hit the first on five minutes before Lampard struck twice to take his season's tally to 13. It ended Birmingham's 15-match unbeaten run.
Ancelotti added: "It is good to be back on top of the table.
"We still have a game in hand, that is important as Arsenal and United play each other on Sunday."
Didier Drogba and Salomon Kalou will be back after the African Nations Cup for Saturday's Burnley trip.
And Ancelotti says Drogba will go straight back into his team - even though Chelsea won all four games without him.