MAGILL, Circuit Judge.
James Gibson appeals the district court’s denial of a writ of habeas corpus under 28 U.S.C. § 2254, arguing that the state failed to prove every element of his drug trafficking offense beyond a reasonable doubt because it tested an inadequate sample of cocaine base, and that the state impermissibly used peremptory strikes against African-American venirepersons. We affirm.
I.
On May 23,1991, St. Louis, Missouri police officers Mark Grman and John Winter observed appellant James Gibson, an African-American, drop a paper cup to the ground. When asked by the officers to pick up his litter, Gibson denied having dropped the cup. Upon investigating, the officers found that the cup contained pieces of what appeared to be cocaine base, and placed Gibson under arrest.
Gibson was tried before a jury in Missouri state court. During voir dire, the state used all of its peremptory challenges to strike seven African-Americans from the jury, giving as reasons either that the venirepersons had relatives who had been prosecuted or convicted for criminal offenses, had work schedules which conflicted with jury service, or equivocated over their ability to follow jury instructions. During trial, the state presented evidence from criminalist Mary Taylor that a sample of the material in the cup tested positive for the presence of cocaine base, and that all of the material in the cup had a uniform texture and color. The total weight of the material in the cup was 3.69 grams, although the piece tested by Taylor weighed less than 2 grams. The jury convicted Gibson for trafficking drugs in the second degree, Mo.Rev.Stat. § 195.223.3(1) (possession of more than two grams of a substance containing cocaine base), and he was sentenced to ten years imprisonment. Gibson’s conviction was affirmed on appeal to the Missouri Court of Appeals; see State v. Gibson, 856 S.W.2d 78 (Mo.App.1993).
II.
Gibson first argues that the state failed to prove beyond a reasonable doubt that he possessed in excess of two grams of cocaine base, because the sample tested by Taylor weighed less than two grams. On collateral review of the evidentiary sufficiency of a state court conviction, we must determine “whether, after viewing the evidence in the light most favorable to the prosecution, a rational trier of fact could have found the essential elements of the crime beyond a reasonable doubt.” Haymon v. Higgins, 846 F.2d 1145, 1146 (8th Cir.1988) (citing Jackson v. Virginia, 443 U.S. 307, 319, 99 S.Ct. 2781, 2789, 61 L.Ed.2d 560 (1979)). In this case, the state did not have to test every particle of the cocaine base to prove its nature; indeed, “[p]roof of the existence of a controlled substance need not be by direct evidence” at all, United States v. Meeks, 857 F.2d 1201, 1204 (8th Cir.1988). We have “affirmed the use of random testing to establish that a substance contains cocaine base” for sentencing purposes, United States v. Johnson, 944 F.2d 396, 404-06 (8th Cir.), cert. denied, 502 U.S. 1008, 112 S.Ct. 646, 116 L.Ed.2d 663 (1991), and hold that this method is also valid tó prove the elements of an offense. The evidence presented to the jury in this case, including the test results of a sample of the material possessed by Gibson and testimony that all of the material was similar in texture and color, was sufficient to prove that Gibson possessed in excess of two grams of cocaine base beyond a reasonable doubt.
HI.
Gibson next argues that the state violated Batson v. Kentucky, 476 U.S. 79, 106 S.Ct. 1712, 90 L.Ed.2d 69 (1986), by striking African-Americans from the jury because of their race. We apply a three-part analysis to a Batson claim. See Purkett v. Elem, — U.S. -, ---, 115 S.Ct. 1769, 1770-71, 131 L.Ed.2d 834 (1995) (per curiam). Assuming that Gibson has made a prima facie case of racial discrimination, step one in our analysis, we conclude that at step two the state successfully rebutted that prima facie case by stating race-neutral reasons for its use of peremptory strikes; see id. at -, 115 S.Ct. at 1771. We note that, at this stage, a court does not weigh the plausibility of the reasons given by the state, but merely determines whether the reasons are facially race-neutral. It is only at step three that “the persuasiveness of the justification becomes relevant — the step in which the trial court determines whether the opponent of the strike has carried his burden of proving purposeful discrimination.” Id. At this step, “implausible or fantastic justifications may (and probably will) be found to be pretexts for purposeful discrimination.” Id. However, “the ultimate burden of persuasion regarding racial motivation rests with, and never shifts from, the opponent of the strike.” Id. Whether a race-neutral explanation is pretextual for discrimination is a question of fact, see Jones v. Jones, 938 F.2d 838, 841 (8th Cir.1991), and in “habeas proceedings in federal courts, the factual findings of state courts are presumed to be correct, and may be set aside, absent procedural error, only if they are ‘not fairly supported by the record.’ ” Purkett, — U.S. at -, 115 S.Ct. at 1771 (quoting 28 U.S.C. § 2254(d)(8)). We conclude that the state courts’ factual findings that the state’s raeially-neutral reasons were not a pretext for discrimination were amply supported by the record, and that the district court did not err in denying Gibson’s petition for a writ of habeas corpus.
Accordingly, we affirm the judgment of the district court.
. The Honorable Jean C. Hamilton, United States District Judge for the Eastern District of Missouri, adopting the report and recommendation of the Honorable Catherine D. Perry, formerly United States Magistrate Judge for the Eastern District of Missouri, since appointed United States District Judge for the Eastern District of Missouri.