Does appellant waive his right to object to impeach his credibility by testifying himself about a guilty plea to a state court drug charge?

We disagree. Recent circuit authority establishes that appellant, by testifying himself about the state court plea during his direct examination, has waived his right to object to such impeachment. See United States v. Williams, 939 F.2d 721 (9th Cir.1991). At trial, but before appellant's direct examination, the district court ruled that it would allow the government to impeach his credibility with the introduction of a state methamphetamine drug charge to which he pleaded guilty but had not yet been convicted or sentenced. Perhaps to soften the sting of the guilty plea evidence, appellant's trial counsel elicited the fact of the plea on direct examination. During his cross-examination, the government also went into the guilty plea in an effort to impeach appellant's credibility.