But whizzkid Alex Chamberlain was the spark behind the win.
Two bookable fouls on the teenager by Carlisle's Gary Borrowdale, making his first start for the club, meant the visitors were controversially reduced to 10 men just before the break.
Within a minute of the sending off Lambert had put the Saints ahead - with a lot of help from the 17-year-old Chamberlain. He turned superbly on Guly Do Prado's cross and dinked the ball into the six-yard box for the 43rd-minute winner.
Carlisle's only effort on goal in the first half was from Lubomir Michalik on the half-hour, but his header was saved by Kelvin Davies.
Saints went close through Dany N'Guessan before Lambert netted and it was damage limitation for the Cumbrians in the second half. Another tame header from Michalik in the 57th minute was the closest Carlisle got to an equaliser.
Chamberlain deserved a goal and came close in the 65th minute. A wonderful one-two with the returning Adam Lallana put the youngster clean through, but Carlisle goalkeeper Adam Collin got down well to save.