Singer-actressJennifer Lopez yesterday denied published reports that suggested she and "Dancing With the Stars" professional dancer Maksim Chmerkovskiy might be dating. "No I'm not. #rumors #nottrue," Lopez, 44, tweeted in response to Pittsburgh radio station WLTJ-FM having tweeted that, "JLo broke up with Casper Smart on FRIDAY and is already dating someone new!" When a fan asked Lopez to clarify whether the singer was denying the breakup or denying dating someone new, Lopez tweeted back, "No I'm not. (dating anyone new already.)" Lopez performed with singer Pitbull, 33, and Brazilian artist Claudia Leitte, also 33, during the opening ceremony of the 2014 FIFA World Cup Thursday in Sao Paulo, Brazil. FIFA earlier in the week had stated that Lopez had canceled due to unspecified production issues. A rep for the singer-actress later countered that earlier reports of a cancellation by Lopez had been "premature."