St. Louis Cardinals pitcher Carlos Martinez is ferociously disputing a lawsuit -- in which the 24-year-old is accused of giving a woman non-life threatening STDs ... after swearing he was clean.
The woman behind the suit, filed in district court in Miami, claims she began a romantic relationship with Martinez in 2012 -- and the two had an on-and-off relationship for years.
According to the suit, the two reconnected last year -- and began having sex again on Dec. 16th. Two days later, the woman claims she began to feel ill and later tested positive for multiple STDs.