Edward Lee Williams appeals from the denial by the district court 1 of his motion for a new trial under Fed.R.Crim.P. 33. Mr. Williams was convicted of a drug offense, see 21 U.S.C. §§ 841(a)(1), 841(b)(1)(C), 851, and his conviction was upheld on appeal. See United States v. Williams, 340 F.3d 563 (8th Cir. 2003). He maintains that new evidence, in the form *984 of testimony from his sister, was sufficiently exculpatory to entitle him to a new trial.

The district court held that the sister’s testimony did not qualify as newly discovered evidence under the relevant rule and that the testimony was so lacking in credibility that it was not likely to produce an acquittal. See United States v. Yerkes, 345 F.3d 558, 562 (8th Cir. 2003). After a careful review of the record, and a consideration of the well-known legal principles that guide the case, we affirm the judgment of the district court on the basis of its well-reasoned opinion.