 Green's first season in single seater formula cars was spent in the British Formula Renault Winter Series in 2001, in which he achieved a best race finish of 2nd place.The 2002 season was spent in the British Formula Renault championship with Fortec Racing, finishing the year as championship runner-up with two race wins.He also made a one-off appearance in the Formula Renault Eurocup with Fortec's European operation.