A Detroit Lions fan is going scorched earth in court after his viral sideline clash with Steelers star DK Metcalf — and he’s swinging for a MASSIVE payday.

Michigan man Ryan Kennedy filed a lawsuit in Wayne County Court on Tuesday … demanding a jaw-dropping $100 million over a Dec. 21 dust-up with Metcalf at Ford Field that blew up across the internet.

Kennedy is now turning to the courts … going after Metcalf, the Pittsburgh Steelers, ex-NFL wideout Chad Johnson, Shannon Sharpe‘s Shay Shay Media, and more … claiming they spread what he calls “defamatory and life-altering” claims about him after the incident.

The drama dates back to the Lions vs. Steelers game when Metcalf appeared to take a swing at Kennedy during the second quarter — an incident that ultimately earned the wide receiver a two-game NFL suspension.

Things escalated the next day when Johnson claimed on the “Nightcap” podcast that Metcalf told him Kennedy hurled racial slurs at him — including the n-word — and made a derogatory comment about his mother.

Kennedy has strongly denied those accusations from the jump … and is doubling down in his lawsuit, calling the claims completely false and reckless.

Attorney Jon Marko, who represents Kennedy, tells TMZ Sports … “The N-word is the most offensive and inflammatory racial slur in the English language. No other word expresses so much hatred and bigotry. Falsely accusing someone of using that word hurts not only the person falsely accused, but hurts every victim of racial hatred and bigotry.”

In legal docs, Kennedy alleges Metcalf fed Johnson bad information that sparked the viral narrative, which he says torpedoed his reputation. He’s also suing Metcalf for assault and battery … while saying the Steelers are legally responsible for his conduct.

Kennedy isn’t stopping there, either. He’s also targeting Ford Field, claiming stadium officials failed to provide proper barriers or security measures to prevent players from reaching into the stands and getting physical with fans.