RYAN TAYLOR netted a goal in each half to take Wigan eight points clear of the drop zone but boss Steve Bruce remains cautious.
He said: "We can't say that we're safe yet, although it's a step closer.
But we've got a nice easy one next week at Chelsea!
"Our first-half performance was arguably the best since I came here."
Birmingham, whose fate was sealed when skipper Damien Johnson was sent off for a two-footed lunge just before half time, made no excuses.
Boss Alex McLeish said: "The lunge has been outlawed in the game. More and more refs now show a red card.
"It was tough playing with 10 men for such a long time. It's hard enough for us when we're playing with 11."