A 93rd minute penalty from Liverpool captain Steven Gerrard broke Ludogrets hearts as they looked destined to claim a famous point at Anfield in their first ever UEFA Champions League match.
Mario Balotelli's first goal for Liverpool with ten minutes broke the deadlock after it seemed nothing could break down their Bulgarian opponents, but Dani Abalo scored in the 90th minute to send the travelling fans into hysteria.
However it was not to be for the Bulgarian champions, as a poor pass back to goalkeeper Milan Borjan allowed Javier Manquillo to nick the ball away from him and his lunge sent the on-loan Spaniard sprawling.
Not one to feel pressure, Gerrard stepped up and coolly sent the Canadian goalkeeper the wrong way to start Liverpool's Champions League journey with a win.
As to be expected, the home side looked to take the initiative early with Raheem Sterling, Balotelli and Adam Lallana in the thick of the action.
However Ludogorets held firm and soon became more confident in themselves, with Marcelinho probably unlucky not to win a penalty when Dejan Lovren used his arm to floor him inside the area, but nothing was given.
The best chance of the half fell to Lallana, though, when the England international was picked out by Jordan Henderson but he couldn't apply the finish and Ludogorets held on until half time.
Liverpool continued to impose, once again failing to threaten with any real integrity, and they were very lucky not to fall behind after Roman Bezjak exposed the Reds' defensive flaws but could only find the post when he should have scored.
After Lucas slammed a shot so high it nearly went into Goodison Park, Alberto Moreno's cross wasn't dealt with properly and Balotelli stabbed home in front of the Kop to register his first strike for his new side since signing from AC Milan for around $26 million (£16 million).
The Italian nearly made it two not long after when he fired a shot goalwards, but it was well saved by Borjan as Liverpool pressed for a second.
As they pushed forward though, Ludogorets launched a perfect counter attack and Younes Hamza slid in Dani Alabo, who rounded Liverpool 'keeper Simon Mignolet to finish with ease.
Just when it looked like they might claim one of their all-time great results, a poor backpass meant Borjan had no choice but to bring down Manquillo, with Gerrard easily putting away the resulting penalty as a huge sigh of relief swept across Anfield.