Liverpool - Steven Gerrard has scored a 93rd-minute penalty as Liverpool scraped past competition debutants Ludogorets Razgrad 2-1 on their return to the Champions League after a five-year absence on Tuesday.
After labouring to break the Bulgarian champions down, Liverpool took an 82nd-minute lead through Mario Balotelli, only for visiting substitute Dani Abalo to equalise in the first minute of stoppage time.
But with Ludogorets on the brink of a memorable shock result, their goalkeeper Milan Borjan -- who only joined the club on Sunday -- felled Javi Manquillo and Gerrard gave the hosts victory from the spot.
It was a cruel finale for Georgi Dermendzhiev's side, who must now rouse themselves for the challenge of hosting defending champions Real Madrid in their next Group B game on October 1.
Shorn of the injured Daniel Sturridge, Liverpool laboured in attack, and manager Brendan Rodgers will expect significant improvements ahead of their next outing away to Basel.
Liverpool's starting XI featured five players who were sampling the Champions League for the first time, including Raheem Sterling, who had started Saturday's 1-0 loss at home to Aston Villa on the bench.
Ludogorets, meanwhile, gave a debut to Canadian goalkeeper Borjan, who was only signed by the club on Sunday after they lost Vladislav Stoyanov to suspension and Ivan Cvorovic to injury.
Although Liverpool quickly assumed control, they did not test Borjan until the 21st minute.
Balotelli had a shot blocked by Aleksandar Aleksandrov following a neat turn and Adam Lallana's follow-up obliged Borjan to make a two-handed parry.
The visitors did not seem daunted by the occasion and after Marcelinho had seen a penalty appeal turned away, Cosmin Moti -- the Romanian defender who saved two penalties in Ludogorets' shootout win over Steaua Bucharest in the play-off round -- headed over.
Liverpool finished the first half strongly, but Lallana dithered when presented with a sight of goal by new vice-captain Jordan Henderson, allowing a defender to block, and Dejan Lovren headed over from a corner.
Success continued to elude the home side early in the second period, with Henderson picking out Manquillo, only for the Spanish right-back to lift the ball into the Kop.
Roman Bezjak gave Liverpool a scare by toeing a shot over after the hosts switched off at a throw-in and Rodgers reacted by introducing Lucas Leiva and Fabio Borini for Lallana and the wasteful Philippe Coutinho.
Borini joined his fellow Italian Balotelli up front and almost made an instant impact, but Borjan athletically tipped his header from Manquillo's right-wing cross over the crossbar.
Bezjak then came within inches of giving the visitors a shock lead when he slammed a shot against the post after Marcelinho nutmegged Mamadou Sakho with a through ball. Yordan Minev steered the rebound narrowly wide.
Borini headed wide, but just when Ludogorets looked set to hold out, Balotelli beat a pair of defenders to a cross from Moreno before expertly steering a shot past Borjan to claim his first goal for Liverpool.
After Borjan had saved from Balotelli, Abalo appeared to have given Ludogorets a famous point when he rounded Simon Mignolet to equalise.
But Borjan's rash lunge on Manquillo allowed Gerrard -- the only survivor from Liverpool's last Champions League game in 2009 -- to spare the home side's blushes.