the injury forced carlisle to miss the first eight months of the 2006–07 premier league season, and he eventually returned to full training in february 2007. he played in two reserve team matches for watford in order to regain some fitness, hoping to break into the first team and make his premier league debut. on 2 march 2007, carlisle joined local rivals luton town on a one-month emergency loan deal in an attempt to return to full match fitness. he made his debut for luton the following day in the 3–2 away defeat to wolverhampton wanderers in the championship, coming on as a substitute for matthew spring, who had himself joined the club from watford earlier in the season after failing to break into the first team. carlisle went on to play five matches for luton. he made his final appearance on 31 march 2007, in a 0–0 draw with burnley at turf moor, before returning to watford on 2 april 2007. he finally played his first premier league match on 9 april 2007, starting in the 4–2 victory over portsmouth. he was selected to play in the team's following match, an fa cup semi-final against manchester united, but despite being named man of the match for his performance, watford were defeated 4–1 at villa park. carlisle went on to play in watford's following three league matches of the season as their relegation back to the championship was confirmed after a 1–1 draw with manchester city at vicarage road.