Jim Magilton lost possession with a poor backpass in the seventh minute and seconds later Colin Murdock was harshly adjudged to have fouled Krassimir Balakov for a penalty, which the veteran World Cup star converted.

Mark Williams headed the Northern Irish level on 15 minutes before Martin Petrov fired Bulgaria back in front two minutes later.

Ian Nolan replaced Aaron Hughes, who failed a late fitness test on his calf injury, in the only change from the starting XI who performed so well against the Czechs on Saturday.

For Bulgaria, Georgi Markov and Biser Ivanov started despite staying out on the town until 4am on Sunday following the team’s victory over Iceland.

The away side needed to make a solid start to have any chance of leaving CSKA Sofia’s Balgarska Armia’s stadium with anything.

However for the third successive match they conceded an early goal.

Magilton gave away possession with a slack backpass to put the defence in trouble. Marian Hristov laid the ball off for Balakov, who burst into the box and went down under a challenge from Murdock.

The penalty award seemed harsh and Murdock was incensed by referee Vladimir Hrinak’s decision.

It made no difference and Balakov, who will be 35 tomorrow, picked himself up to slot home the opening goal.

Back came Northern Ireland and in the 15th minute Williams headed them level with his first international goal on his 16th appearance.

Michael Hughes swung over a corner from the left and Williams powered the ball home from six yards out.

Sammy McIlroy ran on to the pitch to celebrate only to be told off by a FIFA official, but the manager did not care.

McIlroy’s joy was short-lived and two minutes later the Bulgarians went back in front.

The Northern Irish failed to deal with an attack down the left and when the ball fell to Martin Petrov he scored from around 14 yards out with a low shot into the far corner.

That goal, coming so soon after the equaliser, was a body blow for the away side and Roy Carroll did well to save a long-range efforts from Balakov and Krassimir Tchomakov.

The Northern Irish rallied and Hrinak made a decision they agreed with when he booked Dimitar Berbatov, who went close with a header, for diving in the box.