United Kingdom, Jan. 3 -- Maren Morris had "the worst sinus infection" days before her New Year's Eve performance.

The 35-year-old pop-country star's face "swelled up" and had to fight off the serious health ordeal prior to entertaining the crowd in Times Square, New York, with her hits, such as The Bone, The Middle, and 80s Mercedes, during Dick Clark's New Year's Rockin' Eve with Ryan Seacrest on December 31.

Maren uploaded a photo of her heavy, patchy and red face to her Instagram Stories and penned alongside it: "Sorry jumpscare but days leading up to my performance, I had the worst sinus infection of my life and it swelled up my face and then proceeded to evolve into some insane skin reaction. (sic)"

The singer avoided her set fro...