Steve Sarkisian has been fired after 18 games as head coach of USC. Getty Images

The USC Trojans travel to South Bend, Indiana, to face the Notre Dame Fighting Irish Saturday, but talk about the famed rivalry has been drowned out by news of yet another setback for the program. After athletic director Pat Haden announced Sunday that Steve Sarkisian would take a "temporary leave of absence," the school announced Monday that Sarkisian had been fired.

Offensive coordinator Clay Helton, who has served as an assistant since 2010, will take over as interim head coach.

"After careful consideration of what is in the best interest of the university and our student athletes, I have made the decision to terminate Steve Sarkisian, effective immediately," Haden said in a statement.

"I want to thank Clay Helton for stepping into the interim head coach role, and I want to add how proud I am of our coaching staff and players, and the way they are responding to this difficult situation.

"Through all of this we remain concerned for Steve and hope that it will give him the opportunity to focus on his personal well-being."

While Haden didn't provide specifics Sunday, it is widely believed that the decision was related to Sarkisian's use of alcohol. During a booster event before the start of the season, Sarkisian appeared drunk and made inappropriate comments in a speech, with Haden having to pull him off the stage. Sarkisian would later apologize for his behavior and said he would seek treatment.

Sarkisian, 41, was the second full-time coach after nearly a decade under Pete Carroll, and had been the first head coach hired by Haden. When Carroll departed for the Seattle Seahawks, then-athletic director Mike Garrett hired former offensive coordinator Lane Kiffin in what was expected to be a rebuilding effort while under NCAA sanctions. But after more than three seasons under Kiffin, and controversies under his watch involving jersey switching and deflated footballs, Haden decided to fire Kiffin following a 62-41 loss to Arizona State in 2013.

It was Sarkisian who would eventually take the helm in 2014 after highly popular assistant coach Ed Orgeron's stint as the interim head coach. Sarkisian, who had previously served as an offensive coordinator and worked on the same coaching staff with Kiffin, was hired under the intention that he would renew stability to a program coming off sanctions. At Washington, he had boosted a program in the Pac-12 cellar to a respectable standing, and left Seattle with a 34-29 record.

But Sarkisian failed to lift USC, and his alcohol-induced tirade at the booster event raised skepticism that he was the right man for the job. On Monday, the Los Angeles Times did extensive research on his drinking habits at USC and Washington, disclosing that players and others were fully aware of his alcohol consumption.

As head coach, Sarkisian finished with just a 12-6 record -- unimpressive for a program traditionally loaded with top talent. USC entered the 2015 season as the No. 8 team in the nation, and with Saturday's home loss to Washington, 17-12, the Trojans dropped out of the Top 25. USC had entered the matchup as 17-point favorites but looked uninspired and unprepared from start to finish.

It's unclear what the future holds for Sarkisian's future coaching endeavors, but his situation has similarities with former University of Michigan head coach Gary Moeller. After serving as an assistant for several years, Moeller took a head coaching job with Illinois in 1977. He would later return to Michigan and eventually became head coach of the Wolverines from 1990-94. Despite a successful campaign, Moeller was forced to resign after a drunken incident at a restaurant. But after a year, he would accept a job as a tight ends coach with the Cincinnati Bengals, and then as a linebackers coach with the Detroit Lions, who would later promote him to head coach.

Sarkisian is known for developing quarterbacks. While an assistant, he was praised for his efforts in the improvement of future NFL quarterbacks Matt Leinart and Mark Sanchez. Under Sarkisian, current USC quarterback Cody Kessler had progressed into a Heisman Trophy candidate.

On Monday, Carroll sympathized with Sarkisian. In 2001, Sarkisian had joined Carroll's coaching staff at age 27.

"It breaks my heart to see how this has gone," Carroll told 710 ESPN Seattle. "But he recognizes it, and he's going to do something about it, so this is the day the turn occurs."

"I'm grateful for everybody around him that he's finally figured it out. ... This is going to take a long time. This is big battle, and we'll pull for him all the way."