The Irish international came in for Paul Stalteri at St Andrews and played his part in the clean sheet and vital victory.
'Steo' had been in fine fettle for the reserves - including a couple of cracking goals - and took that form into his seventh start of the season.
"It was great to be in the team again and playing at right-back," reflected Steo at Spurs Lodge. "Things have been going well in the reserves and I was confident - there was no point getting worked up beforehand and I just wanted to go out there and play my game.
"The fact that I played right-back helped as well because it's my natural position.
"It was my chance so I wanted to first of all defend and help us keep a clean sheet and when I got the opportunity, try to get forward.
"Birmingham are fighting for their lives and made it tough for us in the first half-hour but we battled through that, scored two goals, kept a clean sheet and won, so that was all that mattered."
Steo is now looking to feature in as many of our eight remaining 'cup finals' between now and the end of the season.
"There is great excitement around the club and everyone feels it," he added. "There is a real buzz around the place.
"Every since I've been at the club it hasn't been like this at this stage of the season, we've always been mid-table and fighting for pride.
"We almost did it last season and this season we've taken it a step further.
"Every game is going to be like a cup final but hopefully we'll apply ourselves like we did against Birmingham. If we can stay solid at the back we've got players like Jermain Defoe, Robbie Keane and Mido and we're always confident they can come up with a goal."
Stephen Kelly said he relished the return to his favoured right-back role as he was handed his chance in the 2-0 win at Birmingham.