The Sixers will take on the Toronto Raptors Thursday in Game 3 of the Eastern Conference semifinal series. And once again the lifelong Sixers fan affectionately known as “Old Man Knees" (due to his tendency to kneel during games) will be sitting courtside.

Alan Horwitz, 76, a real estate developer and longtime Sixers season ticket holder, went viral earlier his week thanks to his antics during the first two games of the series. Sitting courtside at Scotiabank Arena in Toronto, Horwitz — wearing a “sixth man” white jersey — held up a large Sixers sign every time Philadelphia scored a basket, annoying Raptors fans.

Horwitz will once again be seated courtside tonight at the Wells Fargo Center when the game begins at 8 p.m., though that’s hardly a surprise, considering he’s been a regular at Sixers games for more than four decades. According to the team, Horwitz has been a Sixers season ticket holder for roughly 42 years, but his support dates back to the 1960s, when he watched legends like Wilt Chamberlain and Hal Greer from the rafters at Convention Hall.

Through the Sixers, Horwitz declined to be interviewed.

Over the years, Horwitz has had several brushes with fame. Back in 2012, the white-haired Sixers fan became a YouTube sensation after confronting former Los Angeles Lakers star Kobe Bryant on the baseline following a play.

“The ball was out of bounds, and he thought it was his ball,” Horwitz told the Sixers in a team video. “And I was just telling him, ‘Get down the other end of the court, fellah. The ball’s going this way, not that way.’"

Later that year, Horwitz’s passion led to him being ejected from Game 1 of the Sixers’ Eastern Conference semifinal playoff series against the Boston Celtics. Horwitz was once again seated courtside at TD Garden when former Celtic Rajon Rondo fell into the Sixers fan’s lap going after a ball that went out of bounds.

“I’m surrounded by Celtics fans who paid a zillion dollars for their seats. They are not happy with me," Horwitz told the Daily News at the time. “As the Celtics are coming in from a timeout, Rondo walks over and bumps me with his shoulder. I bump him back, curse him and tell him, ‘You’re acting like a punk!’ ”

Horwitz was warned by security following the incident, and later ejected after he brushed former Celtics guard Avery Bradley on the baseline. But Horwitz was able to finish watching the game from former Sixers CEO Adam Aron’s box.

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