Norwich City 0 Charlton Athletic 1
City's crowd of just under 14,000 was some 10,000 down on the average gate for league games, suggesting that season ticket-holders stayed away in large numbers.
Norwich kicked off attacking the Barclay End goal, but were behind inside the sixth minute when Nicky Bailey's through ball found its way to Ambrose all too easily from the Norwich perspective and he calmly slotted a right-foot shot inside David Marshall's left-hand post from some ten yards.
It took Norwich 20 minutes before they put the visitors under any real pressure, but Charlton responded by getting men behind the ball and Norwich showed no sign of breaking through the solid defence.
Two minutes from half-time Carl Cort did win a header in the Addicks' penalty area, but placed it too close to the keeper.
Adam Drury was replaced by Ryan Bertrand at half-time, but it made little difference to the pattern of play.
Ten minutes into the half Arturo Lupoli's shot was deflected for a corner from which Cort headed goalwards, only to see Darren Randolph tip the ball over the bar.
After 61 minutes Marshall was called into action saving Mark Hudson's header.
Lupoli got in a header that went wide and Randolph saved from Wes Hoolahan and Gary Doherty as Charlton deservedly held on to face Sheffield United in the fourth round.