Rex Features
According to The Playlist, Quaid dropped out due to "scheduling conflicts" with the movie Soul Surfer.
Paxton replaces Quaid as the father of a secret agent, played by MMA fighter Gina Carano, who is double crossed by a teammate on a mission.
Knockout also stars Michael Douglas, Ewan McGregor, Channing Tatum, Antonio Banderas, Michael Fassbender and Mathieu Kassovitz.
The film is scheduled to being shooting in Dublin next Monday.
