Wisconsin quarterback Graham Mertz, who had a record-setting first career start Friday, tested positive for COVID-19 over the weekend, according to the Wisconsin State Journal and the Milwaukee Journal Sentinel.

Both newspapers reported Sunday, citing sources, that Mertz had an antigen test come back positive. Mertz will take a polymerase chain reaction (PCR) test to confirm the result. If confirmed, Mertz would have to miss a minimum of 21 days, according to the Big Ten's protocols for athletes who test positive.

Team officials did not immediately confirm the reports. Coach Paul Chryst is scheduled to speak to reporters Monday morning. A source told the Journal Sentinel that Wisconsin has had several false positives since beginning daily antigen testing last month.

Mertz, a redshirt freshman, was virtually flawless Friday in a 45-7 win over Illinois. He completed 20 of 21 passes for 248 yards and five touchdowns. He set team records for single-game completion percentage (95.2) and touchdown passes. Mertz completed his first 17 pass attempts, matching a team record for consecutive completions.

No. 9 Wisconsin is scheduled to visit Nebraska this week, followed by games against Purdue (home) and No. 13 Michigan (road). Sophomore Chase Wolf would likely step in for Mertz if he has to miss time.

Mertz moved into the starting role after senior Jack Coan suffered a foot injury in preseason camp and underwent surgery Oct. 21. Coan, who started 18 games the past two seasons, is out indefinitely. Mertz, a native of Overland Park, Kansas, is considered the top quarterback recruit in Wisconsin history. ESPN rated him as the top pocket passer and No. 21 overall player in the 2019 recruiting class.