Arizona's Allonzo Trier has been declared ineligible for the reappearance of a banned substance that led to a 19-game suspension last season.

The NCAA notified the school on Thursday that the preseason All-America junior guard tested positive for trace amount of the substance late last month.

Arizona says the amount detected was minuscule by scientific standards and appeared to be a remnant of the undisclosed performance-enhancing drug Trier said he unknowingly ingested last season. The NCAA agreed, the school said.

Arizona is appealing the decision and hoping Trier will regain his eligibility soon. The 14th-ranked Wildcats (21-6, 11-3) have four regular-season games left before the Pac-12 Tournament starts March 7 in Las Vegas.

Trier sat out the first 19 games in 2016-17 after testing positive for the drug. He won an appeal with the NCAA and was allowed to return after the substance cleared his system.

"I have never knowingly taken a banned substance," Trier said in a statement last season. "After finding out that I was given a banned substance by a well-intentioned, but misguided person not associated with the University after an injury, I presented this information to the NCAA. The NCAA agreed that I had no knowledge of receiving the substance and my eligibility was restored."

Trier has been a key cog in the Wildcats' bid to win their fourth Pac-12 title in five seasons. He is second to freshman Deandre Ayton for the team scoring lead at 19.6 points per game and second with 3.2 assists.

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