Wisconsin won the NCAA title last season. (Jamie Schwaberow/NCAA Photos via Getty Images)

Defending champion Wisconsin volleyball ended its regular season on an 18-match winning streak.

The Badgers have not lost since Sept. 25, even as the team endured a tough Big Ten schedule and the turmoil of a photo leak investigation, and now they enter the NCAA tournament with a 25-3 overall record and the No. 1 seed.

The University of Wisconsin athletic department announced on Oct. 19 the investigation into a a leak of private photos and videos of Badgers women’s volleyball players, which were then shared on the internet.

At least one of the photos appears to have been taken after the team won the Big Ten title last November and shows members of the team posing with their sports bras lifted, the Milwaukee Journal Sentinel reported.

The athletic department called the leak a “significant and wrongful invasion” of the athletes’ privacy. Yet even after the off-court issue, which highlighted the vulnerable position of college athletes, the Badgers continued to roll.

Wisconsin finished its conference season Saturday with a 3-1 win against Ohio State, clinching a 19-1 conference record and the Big Ten title. The only loss came on Sept. 25 against Minnesota.

“There was so much learning that came from our one loss against Minnesota,” coach Kelly Sheffield said. “That was really important for where we are right now. There was so much opportunity for us to learn throughout the course of the year and I am so proud of them.”

The 18-match winning streak is tied for the second-longest winning streak in program history. The 19-1 conference record is tied for the best conference record in program history.

Wisconsin already has sold out all-session tickets to its first- and second-round matches in the NCAA tournament. The Badgers will start their quest for a repeat title at 8 p.m. ET Friday against Quinnipiac.