A second-half strike from midfielder Barry Ferguson - his first goal for the club - was sufficient for City to clinch an away meeting with Everton in the next round.

But the home side were indebted to two fine saves from on-loan keeper Joe Hart for keeping them in the tie before Ferguson struck after 61 minutes.

McLeish said: "Is it a relief? I wouldn't say it was a relief but I'm happy to get the victory from a tough game when we weren't at our best.

"Once again it tells you a lot about the resilience of the players that we can come out on top when not firing on all cylinders - and it was a terrific goal.

"But I have to say that Forest played well and they can count themselves unlucky to be out of the Cup."

McLeish decided to field the same line-up which had held Manchester United to a 1-1 draw at St Andrew's at the weekend.

He said: "I wanted to keep the momentum going that we have at present so I kept the same team.

"The players have not been training recently because of the weather so it is better that they play rather than have two or three days off and lose their sharpness.

"It was important they played tonight with a view to Saturday's game against Portsmouth."

Ferguson used to be a prolific marksman during his days at Rangers but has been asked to alter his game since moving to Blues in the summer in a £1million deal.

McLeish said: "Barry used to score a great number of goals at Rangers. I think he got 18 when we won the treble one season.

"He used to make a lot of forward runs and we had fantastic players who could make the most of him getting into good positions.

"We have asked him to modify his game since he came here and it's been Lee Bowyer who has been getting a fair share of goals. But that was vintage Barry, with the run and finish."

Forest boss Billy Davies made it clear his main priority is the Coca Cola Championship by making seven changes to his starting line-up.

But he was still left to rue missed opportunities in both matches.

He said: "We've now played Birmingham over two games and their goalkeeper has been the man of the match on both occasions.

"This was a big learning curve in terms of it being important to take your chances.

"We should have been ahead in the first half but snatched at everything, but I'm not disappointed at all about the way we played.

"We know Birmingham are 1-0 specialists but we had the chances over the two games to have come out on top.

"But at the moment they have a keeper in Joe Hart who is in fantastic form. I am very proud of the way the people we've put out on the pitch tonight performed and it was a great experience for them."