Liverpool manager Brendan Rodgers admits his side have yet to reach the standard they set themselves last season but was relieved to open their Champions League campaign with a 2-1 victory.
Mario Balotelli's first goal for the club eight minutes from time looked to have won the game only for Ludogorets substitute Dani Abalo to roll in a 90th-minute equaliser for the Bulgarians.
However, captain Steven Gerrard scored an even later penalty after Javier Manquillo was brought down by goalkeeper Milan Borjan to ensure Liverpool's return to Europe's elite club competition after a five-year absence did not fall flat.
"It was very important to get back in the competition but it was always going to be a tricky tie for us because they are the champions of their country and there are not too many bad teams in the competition," Rodgers said.
"Maybe in the first six months we would have drawn and maybe even lost it but we showed the resilience and character in the group and, roared on by the supporters, it was great for us.
"We could do no more than win tonight. We are not at the standard we were last season, that is for sure.
"There is a lot of adaptation going on as we have a lot of players who have come in and are still adapting.
"We are a work in progress. While we do that it is important we win games.
"Tonight was about perseverance, an attribute you need to have, especially at the highest level.
"We kept going, kept pushing and the whole ground really appreciated that."
One of those players still adapting is Balotelli, who got off the mark in his third game following a £16million summer move from AC Milan.
"He is used to scoring. He had two games when he hadn't scored. I just feel with him, he needs to be in the box more," added Rodgers.
"I said to him at half-time make sure when the ball is in wide areas, make sure you are penalty spot and in, not penalty spot and out.
"He is 6ft 3in, great in the air and has great physical strength. His goal showed great touch and a brilliant finish.
"That will give him a whole load of confidence. He is still adapting, trying to get fit, because he has been behind the others in pre-season but he showed his quality tonight and that got us the goal."
Ludogorets coach Georgi Dermendjiev felt his side deserved more on their Champions League debut.
"This is football. It is of course bitter for us because of the result but I am not mad about it," he said.
"I am not blaming the goalkeeper. I am not annoyed or disappointed with him.
"This decision is made in the nick of time so there is nothing to blame for.
"The goalkeeper was upset after the mistake. That is natural but we have a very good team atmosphere and his team-mates and I told him after the game that it is not a big mistake and everything will be fine in the future."
Source: PA
