The BBC said it is unclear whether the singer will be well enough to perform three other shows he has scheduled in the United Kingdom this weekend.
BBC Manchester presenter Karen Gabay said Ne-Yo appeared to be suffering from a "really bad fever" during his truncated performance Thursday night.
"He was doing a Michael Jackson tribute and you could see that he was actually struggling to finish every musical phrase. He kept asking the audience to bear with him," Gabay reported.
"Then he actually was crying," she added. "I thought it was because he had done a couple of Michael Jackson tributes and he was getting a little bit overcome, but it did seem a bit strange. He was very emotional. Then he did a slow song, he was really struggling to move, he was absolutely pouring with sweat, and he went over to a table. He was actually hanging on for dear life and he looked as if he was about to drop then, he looked so ill."
The performer took a long break, then returned to the stage and tearfully told the crowd he had to cut short a concert for the first time in his career, Gabay said.
Organizers then assured the audience the gig would be rescheduled.