Alex Rodriguez reportedly is arguing in his grievance to overturn his 211-game suspension that he believed the substances he received from Biogenesis of America were legal supplements.

The New York Daily News reported the nature of the New York Yankees third baseman's testimony, citing a source with knowledge of the hearings.

Alex Rodriguez reportedly is claiming he didn't know the substances he received from Biogenesis of America were illegal supplements. AP Photo/David Karp

Rodriguez's stance is contrary to that of Biogenesis founder Tony Bosch, who is cooperating with Major League Baseball. Bosch has confirmed the authenticity of his correspondence with Rodriguez and documents from his now-closed anti-aging clinic in Coral Gables, Fla., the newspaper reported.

Rodriguez's spokesman, Ron Berkowitz, released a statement Wednesday emphatically refuting the Daily News report.

"We cannot provide any details of this hearing as the Chair of the Arbitration Panel has issued an order prohibiting all parties from commenting publicly on the confidential proceedings, but what is being reported is NOT true," the statement said.

Rodriguez's attorneys are expected to cross-examine Bosch on Wednesday and are likely to attack his credibility. The Daily News reported that attorneys are expected to argue that Bosch was reportedly paid by MLB for evidence collected in its investigation and told that he would be dropped from a lawsuit if he cooperated.

A three-time AL MVP, Rodriguez was suspended Aug. 5 for alleged violations of baseball's drug agreement and labor contract. Because he's a first-time offender under the drug program and the players' association filed a grievance to force an appeal, a suspension can't start until it is upheld by an arbitrator.

The union argues the discipline is without just cause and is excessive. If the case doesn't settle, a decision by arbitrator Fredric Horowitz is expected this winter.

Rodriguez was among 14 players penalized by MLB this year following the sport's investigation of Biogenesis of America, which is accused of distributing banned performance-enhancing drugs. The others accepted their penalties, including former NL MVP Ryan Braun, who missed the season's final 65 games.

The hearings, which began Monday in New York, are expected to continue the rest of this week but will not take place next week if they are not finished due to scheduling conflicts, the Daily News reported. In that case, the hearings would resume at the end of this month or in November.

Information from The Associated Press was used in this report.