Martinez and his agent have both declared they're in talks to sign for Atletico over the past week.
But on Sunday, the striker insisted: "We've already sorted it out with the president that I'm going to stay [at Racing] for another six months, and if we qualify for the Libertadores, the whole year."
Martinez made the comments at a club function and were greeted with cheers by fans.
Racing have already rejected an offer of €12.75 million from Atlético. The negotiations will continue, both between the two clubs, and between the player and his representatives. But for now, nothing has been signed.