The Celebrity hitmaker, who celebrated his 10th wedding anniversary with Nashville star Kimberly Williams-Paisley earlier this year (13), became the subject of a National Enquirer article last week (ends22Nov13) amid false allegations he has been hooking up with Underwood behind their spouses' backs.
However, Williams-Paisley is confident there is absolutely no truth to the cheating claims.
Laughing at the suggestion of infidelity, the actress tells UsMagazine.com, "Are you serious? Wow! I hope it helps our careers! That's all I can say."
Paisley and Underwood have become close friends over the years and reunited earlier this month (Nov13) to co-host the 2013 Country Music Association Awards for the sixth consecutive time.
Underwood is married to ice hockey star Mike Fisher.