Tiafoe, a top-ranked junior, won his first Grand Slam main-draw match in doubles this week at the U.S. Open.
ESPN tennis analyst Brad Gilbert told CNBC that Tiafoe was a player to watch. He said there's "a huge, huge hedge fund guy" backing Tiafoe.
Gilbert didn't name Ackman explicitly, but we were able to figure it out.
We got in touch with Ackman, and he told us that Tiafoe has a great story.
"[Tiafoe] has a very compelling life story and he's super-talented. He's a good kid," Ackman told Business Insider by phone. "I'm in a position to be able to help people, and he's the kind of guy you want to back."
Read more: http://www.businessinsider.com/bill-ackman-sponsors-us-open-francis-tiafoe-2014-8#ixzz3BumDsB15