Former six-time Pro Bowl wide receiver Brandon Marshall announced Tuesday he was going from in-between the sidelines to in-between the ropes by launching a boxing career.

Marshall, 35, made the announcement in an Instagram video and said he plans to have his first professional fight in May 2020. The opponent was not named.

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“I’m about to do the unthinkable,” Marshall said. “Thirteen years, NFL. Thirty-five, phenomenal shape. Just went 24 rounds. I’m about to do the unthinkable. Heavyweight champion of the world. Lotta people that try fail.

“I promise you. [Anthony] Joshua, [Deontay] Wilder, [Luis] Ortiz, [Tyson] Fury. All you boys, I can get it. I’m telling you. You’re not that tough, not that strong. Where I come from, and what I’ve been through in my life, I’m built for this. I promise you that. I’ll see you next May.”

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Marshall retired from the NFL after the 2018 season. He played for the Denver Broncos, Miami Dolphins, Chicago Bears, New York Jets, New York Giants and Seattle Seahawks.

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Though he never won a Super Bowl, it appears the 6-foot-5, 232-pounder has his sights set on a heavyweight title.