Pop star Justin Timberlake has apologized to fans for canceling his New York concert Wednesday night due to unspecified "health reasons." The Madison Square Garden show has been rescheduled for Friday. Thursday's performance at the venue is to go on as planned. "Hey NY. There is never an easy way to do this ... Unfortunately, I have to postpone tonight's show to Friday due to health reasons," Timberlake wrote on his website Wednesday. "I am truly sorry to everyone that have tickets for tonight. It kills me to have to do this. I hope to see you all on Friday."