The challenge before Sunday’s match was for Northern Ireland to try and build upon the momentum they have worked so hard to generate.
A narrow defeat away to a physical team in difficult conditions is unlikely to knock the confidence of the team too far. A bump in the road, if you will, rather than derailing progress.
But now, as attentions switch to the next window, the challenge for O’Neill’s young team will be to make sure the defeat in Plovdiv was a one-off and their progression continues in a positive trajectory.
Bradley is adamant that will be the case.
Next up, Northern Ireland face Belarus on 12 October, which will be played in Hungary due to the ongoing conflict in Ukraine.
“We know it is going to be difficult going away to Belarus but I have full confidence already,” added Bradley.
“We have a good bit of momentum from the game so we just have to keep that going.”
And in the second game of the window, Northern Ireland have the chance to get back at the Bulgarians, who travel to Belfast on 15 October.
“Hopefully we can do them back,” Bradley said.
“They will be a difficult game, even at home, but hopefully we can get some revenge.
“We aren’t out of the group yet and the win the other night was good for us, so we’re not done yet.”