Mertz completed 20 of 21 passes for 248 yards and five touchdowns in Wisconsin's 45-7 victory over Illinois on Friday.
Wisconsin quarterback Graham Mertz has tested positive for COVID-19, according to the Milwaukee Journal Sentinel's Jeff Potrykus.
Mertz shined for the Badgers in Wisconsin's opening-night win over Illinois on Friday. The redshirt freshman completed 20 of 21 passes in the 45-7 victory, throwing for 248 yards and five touchdowns.
Wisconsin officials did not comment on Mertz's status. He could still play next week against Nebraska if he registers just one positive test, though a second test will force him to sit out at least 21 days, per Big Ten protocol.
Mertz was slated to be Wisconsin's backup quarterback as the Badgers prepared for their season opener. Starting quarterback Jack Coan underwent foot surgery on Oct. 7, but he hopes to return at some point in 2020.
Wisconsin currently sits No. 9 in the AP Poll. The Badgers will face Nebraska on Saturday, with kickoff slated for 3:30 p.m. ET.