Chicago. May 19,—James S. Jeffries entertains the opinion that Jack Johnson will win from Jack O'Brien in their six round go at Philadelphia tonight. Jeffries thinks O’Brien has gone back considerably and cites the Philadelphian’s battle with Ketchel as an example.In speaking of Uie ligm Jeffries said:“O'Brien is a mighty clever fighter and if it were not for his showing I again at Ketchel 1 would he Inclined .to believe he had an even chance In tonight's battle, but that ftglu sbov-:cd plainly that Jack has gone back. 1 believe that Johnaou will bore in j and force the fighting.”