Jurgen Klopp joked that Adrian's mistake during Liverpool's 2-1 win over Southampton was a rite of passage.
The Spanish goalkeeper overcame an ankle injury suffered when a pitch invader slid into him during the celebrations of their Super Cup win against Chelsea in Istanbul on Wednesday to take his place in the side at St Mary's.
But after Sadio Mane and Roberto Firmino goals had put Liverpool in control, he handed Southampton a lifeline as he dallied on a backpass which was charged down by Danny Ings and ended up in the back of the net.
The Reds had to hang on in the end, recording a club-record 11th successive Premier League victory and making light of their midweek jaunt to Turkey, where they played 120 minutes and did not arrive back home until 4am on Thursday.
Adrian has been thrust into Klopp's side after an injury to first choice Allison, who made a similar mistake in his first few months at the club last season.
And the German said it was only right that Adrian made an error.
"Minute 83, Adrian thought, 'I've played really well so I have to make a mistake like Alli did' and kept the game a little bit open," he said.
"I said to him, 'Finally, it arrived, welcome'. Alli did the same, obviously it is a goalie thing at Liverpool. I have no problem with that as long as we win the game.
"Adrian had a swollen ankle, we played too many balls back to him in that period. I was happy with everything he did today, all the saves he made, all the other stuff.
"The other players need to feel the responsibility for the build-up for the balls back for him.
"He is good with his feet and if you would have seen his ankle on Thursday when we left the plane then you would say that pass for the goal was better than you would have expected. It is all fine.
"He had a clearing session at 10am and I got the message that he was fine. If I got the message that he wasn't fine then I would have had a decision to make.
"He said at breakfast that he was fine and we had to test it."
Liverpool's hectic schedule looked like catching up with them in the first half as Southampton were the better side and had two fine chances to lead through Maya Yoshida and Che Adams.
But Mane's clinical strike in first-half stoppage time put them in front and then Firmino doubled the lead in the 71st minute after a host of other chances went begging.
Adrian's error allowed the hosts back into it and then Ings should have delivered the ultimate penalty to his former club, but he somehow missed from four yards.
Klopp insists his side's midweek exertions had nothing to do with their afternoon on the south coast.
"Southampton is a good team. They defend well, they had good counter attacks, good organisation," he said.
"This afternoon it was difficult again, nothing to do with the game midweek. I said before the game if we had come here with two weeks' preparation it would have been difficult.
"I liked the game a lot. It is not allowed to think too much about Wednesday but I know it, so I was really impressed with how fresh we looked, at the start especially, just how good we were.
"We deserved to win."
Ings will have nightmares about his miss when he goes to bed and so will boss Ralph Hasenhuttl, whose side have now lost their opening two games.
"We stayed in and tried to come back into the game and at 2-1 we could feel there was hope for everybody," he said.
"Ingsy scored once but could be the big hero for us, the second chance to miss was unbelievable. We had three men in the box at that moment and we couldn't get the ball over the line and that was a real pity.
"The guys for what they invested today they maybe deserved one point, but we didn't get it. It's tough to take.
"After the first half it was hard to take, but I think we haven't been so bad. We had big chances to score. We stressed them very early, we tried to give them high pressure and we didn't give a lot of chances away.
"That is the difference, a player like Mane in such a moment with all of his quality and then you are one down."