The New York Yankees, Philadelphia Phillies and Chicago White Sox are believed to be in the running for free-agent superstar Manny Machado this offseason.

But according to Jon Heyman of Fancred, at least three mystery teams may also enter the bidding:

Ken Rosenthal of The Athletic also reported the Phillies, White Sox and Yankees had company, tweeting, "One rival executive hears at least three other teams are in the mix and will meet with Machado's agent, Dan Lozano, at the winter meetings."

Machado and Bryce Harper are the big names in free agency, with each potentially in line for a $300 million contract. It's rare for two superstars in their mid-20s—both are 26—to become available simultaneously in free agency, so each is incredibly valuable.

Machado is one of baseball's more complete players. He's a two-time Gold Glover and four-time All-Star who can play shortstop and third base. But he's just as dangerous at the plate, where he hit .297 with 37 homers and 107 RBI last season, his fourth straight year with at least 33 dingers.

How the Machado negotiations will evolve is less clear. Will teams wait to see where Harper lands before jumping into the fray on Machado, or will they be aggressive in their pursuits? Will any team—such as the Phillies—try to sign both Machado and Harper? Will Machado insist on remaining at shortstop, or will an enormous payday with the condition he move back to third base still entice him?

Machado will control who he sees and when he sees them, as Bob Nightengale of USA Today reported:

Heyman reported the Yankees "like" Machado but won't exceed $300 million to sign him. That could be posturing, but if big spenders like New York fall out of the bidding, it could limit Machado's market. It only takes one big fish willing to bite on a huge contract, however, and reports have consistently suggested the Phillies could shell out major money this offseason.

And there is always the possibility a mystery team or teams, as rumored, could get involved and throw big bucks at Machado. The situation remains fluid, but it's hard to imagine the superstar infielder won't come away with an industry-shaping contract.