Mile Jedinak's header in second half gave visiting Villans a good advantage ahead of the reverse fixture which comes up on Tuesday.
"I know this victory can’t bring anyone back [to the Premier League] but at least, we’ve put some joy on the faces and hopefully it can be the same on Tuesday in the return leg,” Adomah was quoted as saying by Birmingham Mail.
“We’re halfway through, we’ve got an important victory and hopefully we can follow-up on Tuesday. We can’t get too excited at the halfway stage.
“Both teams are in limbo in a way. I know we’ve won and they’ve lost, but the important thing is that we know we can draw on Tuesday night and go through. At the same time we want to win the game. That will give us even more confidence in the final," he added.
The winner of the tie will battle the winner between Birmingham and Fulham in the final at Wembley. Birmingham also head into the return fixture with a 1-0 victory which ended Fulham's 26-game run without a defeat.
Wolverhampton Wanderers and Cardiff City have booked the two automatic qualification slots to the Premier League.