one game at a time (1904)

“If–and it is a big if–Oakland wins ten of the games teh Commuters will be but two or three points behind the champions, and should eleven games be won the Alameda country team will lead. Of course, it doesn’t seem probable that the Lohmanites can get away with such a number of games from the northerners but they only have to win one game at a time, and funnier things have happened.” Le roy Hartley, “Oakland May Yet Win Out,” San Francisco Chronicle, October 23, 1904, p36

No earliest use given in 2009 Dickson Baseball Dictionary