The pair competed in opposite teams on new BBC One entertainment programme Hole In The Wall, which sees celebrities donning silver lycra suits as they try to get through a hole in a moving wall.
According to the Daily Star, Wotherspoon still holds a grudge against Feltz after she publicly branded him a "snake" for his behaviour on Sir Alan Sugar's business series.
An insider told the newspaper: "You could cut the tension between the two with a knife."
Wotherspoon, who is now working as a model, also had to contend with the flirty behaviour of show host Dale Winton.
"He got a lot of attention from Dale," the source revealed. "Afterwards the crew were teasing Alex that Dale had specifically asked to have him on the show, which made him blush."