The newspaper, citing an unnamed source, said Rodriguez is arguing in this week's appeal of his unprecedented 211-game suspension he believed substances he obtained from the now-shuttered Biogensis clinic were only innocent legal supplements.
Major League Baseball, however, contends the embattled third baseman knew they were banned performance-enhancing drugs.
The arbitration hearing at the New York offices of Commissioner Bud Selig began Monday with an opening statement from Rodriguez, and continued through Tuesday with testimony from Biogensis founder Anthony Bosch, who is cooperating with the probe, the Daily News said.
Bosch reportedly corroborated evidence obtained from his clinic's records and also shared his email communications with Rodriguez.
The Biogenesis scandal in August resulted in suspensions for 14 major-league players. Only Rodriguez appealed his suspension, and continued playing for the Yankees through the end of the season.
The hearing became the scene of demonstrations Tuesday when protesters claiming unfair treatment for Rodriguez gathered outside MLB's Park Avenue offices.