Goals from Finn Azaz and Matt Doherty saw Ireland come from behind in Plovdiv to take a 2-1 lead into Sunday's Nations League B playoff second leg against Bulgaria.
Heimir Hallgrímsson's side made a bright start to this first leg away from home but were caught by a fine finish by Marin Petkov after six minutes in what was Bulgaria's first attack of the game.
However, the Irish responded well with Azaz nodding into an empty net in the 21st minute for his first international goal after Troy Parrott cushioned a beautiful ball into his pass after getting on the end of a deep cross by Robbie Brady.
Bulgaria had a penalty shout waved away despite Kiril Despodov going down from a Ryan Manning challenge, but the winger was adjudged to have handled in the process.
Ireland were looking much more likely, however, and Parrott flashed a shot across goal with Nathan Collins not far away from turning it home.
But the lead goal would arrive three minutes before the break as Doherty read the flight of Josh Cullen's long ball forward from the right to perfection to get there before home goalkeeper Dimitar Mitov and glance home.
The Bulgarian goalkeeper injured himself when clattering into Doherty in the process and was replaced for the second half which became quite disjoined with little by the way of clear opportunities.
The onus was on Bulgaria - battling to earn promotion from League C and relegate Ireland in the process - but the closest they came to levelling it up going into Sunday's second leg in Dublin came around 15 minutes from time when Andrian Kraev saw a shot blocked by Dara O'Shea.
"Well, the game wasn't really started when that happened," Hallgrímsson said of losing the early goal when speaking to RTE.
"I was just hoping that we would continue to do what we planned to do and they did. Some really good moves and good play, especially with the ball. Kind of what we wanted them to do, a happier half-time.
"We can do a little bit better. It's only the first game of two, so just keep our heads on the ground and look forward to going to Dublin and playing them in our home."
