Free agent O.J. Mayo is headed to the Mavericks. From our friends at ESPN Dallas:

The Dallas Mavericks and shooting guard O.J. Mayo have agreed to a multiyear deal, according to a source with knowledge of the situation.

Mayo, 24, spent the first four seasons of his career with the Memphis Grizzlies, averaging 15.2 points a game. He is set to join a radically revamped Mavs roster that has added center Chris Kaman, forward Elton Brand, shooting guard Dahntay Jones and point guard Darren Collison in the last five days.

The third overall pick in the 2008 draft broke the news on his Twitter account, saying, "I will be signing with dallas! #Mavsnation."

Not long after, Mavs owner Mark Cuban tweeted: "Welcome to the family OJ. We are fired up !! MFFL Mavs/Mayo Fan For Life !"

Mayo was one of the top available shooting guards and someone the Celtics seemed interested in to help fill the vacancy left by Ray Allen's departure (the two players were reportedly nearly swapped at last year's trade deadline). The Celtics already added former Mavericks shooting guard Jason Terry, but it appears Dallas has softened their own loss by swooping up Mayo.

Boston is likely left focusing on unrestricted free agent Courtney Lee, who met last week with Celtics coach Doc Rivers in Orlando and later admitted Boston was one of his potential destinations. Trouble for the Celtics is that they don't have the necessary available money to entice Lee, and Boston was working on a potential sign-and-trade deal with Dallas over Terry, which might have freed the team's midlevel exception to utilize in the pursuit of a shooting guard like Mayo or Lee.