Patrick Vieira had the last laugh over former fierce rival Roy Keane after the Arsenal hero dropped a savage dig on the Manchester United legend. Roy Keane and Patrick Vieira shared an intense rivalry during the height of Manchester United and Arsenal’s rivalry under Sir Alex Ferguson and Arsene Wenger. Vieira was a key midfield presence for Arsene Wenger at Arsenal, while Keane was a formidable leader and captain for Sir Alex Ferguson at United. Keane hasn’t been afraid to pull no punches towards the 47-year-old Frenchman, including claiming that Vieira would been a United squad player had he…