Taiwo Awoniyi gave Nottingham Forest a vital win over Liverpool, running out 1-0 winners at the City Ground.
The Nigerian striker's second half goal was enough to give the hosts a massive win, proving the level they are capable of after a tough start to the campaign.
It was another frustrating match for Jurgen Klopp and his side, who had chances, but were not clinical enough to be deserving of the victory.
Story of the match
Steve Cooper handed starts to Cheikhou Kouyate and Awoniyi to replace Orel Mangala and Brennan Johnson from The Reds' goalless draw against Brighton in midweek.
Liverpool made five changes from their win against West Ham, with Darwin Nunez and Thiago both unfit.
Trent Alexander-Arnold was also excluded from Klopp's starting lineup.
An even start
Morgan Gibbs-White spun his man well and drove at the heart of the Liverpool midfield, but it came to nothing.
The former Wolves man saw his cross into the box cleared away by Virgil Van Dijk minutes later.
The visitors had their foray forwards when Harvey Elliott lobbed the ball over the Forest defence, which Fabio Carvalho brought down wonderfully, but Dean Henderson was equal to it.
A string of Liverpool corners saw Roberto Firmino go close to heading in the opener for Klopp's side.
Alisson was forced into heading the ball clear in goal for the visitors, but a foul from Kouyate on Elliott relieved the pressure on the Merseyside based team.
Mohamed Salah looked to cut in and shoot, but Neco Williams was on hand to make the challenge to prevent his former teammate from getting a shot away.
Elliott looked to play a through ball to Firmino out wide, but the pass was too strong and went out of play for a Forest goal kick.
Curtis Jones had to be clever to draw a foul on the edge of his own box, as the hosts pressed the Liverpool backline with intensity.
A poor pass from Van Dijk gifted Forest possession, as Awoniyi cut the ball back to Kouyate, but his shot was comfortably saved by Alisson.
Scott McKenna made an important block, after Jones cut the ball back to Salah, but the Scotsman was on hand to send the ball behind for a corner which was cleared.
Gibbs-White and Serge Aurier combined well to bring the hosts up the pitch, but the play became quite erratic between the two sets of players, and it was cleared.
Ryan Yates stole the ball off Jones for the hosts, but it was soon taken off him as he looked to set up a teammate.
Awoniyi cut in from the left-hand side and looked to shoot, but his tame effort was easily held by the Brazilian in Liverpool's goal.
Aurier floated the ball towards the back post, but it was tipped away from danger as Cooper's side looked make their mark in the tie.
Henderson made a comfortable save to deny Salah, who was given the ball by Firmino who had no space to shoot himself.
Forest went straight up the other end, as the ball was played to Jesse Lingard in space, who could only put his strike straight at Alisson.
The pair had broken away and had a great opening despite some pressure from two opposing defenders, but ultimately the chance was wasted.
There was concern for Salah, who went down in the box and looked to be in some discomfort.
He was able to continue though despite walking quite gingerly, holding his back.
Kouyate made a vital interception to prevent James Milner from getting a cross away.
Van Dijk had a wonderful chance to score from the eventual corner, he tried to head the ball to Firmino instead of scoring, but it was nowhere near the goal or the attacker.
The Dutchman had passed up on easily the best chance of the tie so far.
Kouyate made a high challenge with his studs showing, but luckily for the Senegalese midfielder he did not connect with Elliott, he may have been in trouble otherwise.
It was goalless at the break, with Cooper the happier of the two managers.
Forest showed their ability to compete with the top sides before the interval and were deservedly level after 45 minutes.
Awoniyi made an unnecessary foul on Joe Gomez as he passed the ball back to his goalkeeper, but the striker was not booked for the challenge.
Liverpool pressure
Carvalho had the first opening of the second half, as he was picked out in the Forest box, but he could not connect with the effort properly to score.
He had another opportunity soon after, firing over after Salah missed the ball entirely on the volley.
Elliott went down in the box under contact from Steve Cook, but the referee waved away the appeals.
It had been a much better showing from the visitors after the break.
Gomez was caught in possession and bundled Awoniyi over and was booked for the foul.
It was the hosts that had the lead despite the pressure from the visitors, sending the home fans wild.
Williams could only find the post with his effort from a cross, but it handed Awoniyi an empty net to give Forest a shock lead.
Elliott looked for an immediate response at the near post, but Henderson was able to tip the ball away.
Awoniyi played the ball into Gibbs-White who had acres of space, but he hesitated and allowed Milner to make a crucial block.
It could and should have been 2-0 to Forest.
Jordan Henderson and Alexander-Arnold were both introduced by Klopp in an effort to turn the game on its head.
Firmino found himself unmarked from a corner but could only put the ball over the bar.
Liverpool were putting pressure on the hosts, who switched to a back five for the final 30 minutes of the tie.
Kouyate led Forest forward on the counter attack, playing the ball to substitute Johnson, who saw his effort saved.
Jones volleyed the ball towards goal as the game entered the final 20 minutes, but it was easily saved by Henderson.
Yates' effort was not held by Alisson, but it did not fall to Johnson and was eventually dealt with.
Van Dijk looked to be suffering with a knock after a collision with Johnson, but he was able to continue.
Henderson was on hand to make a superb save to deny Alexander-Arnold.
He arrived at the back post and looked to head Liverpool level, but the English goalkeeper was equal to it.
Yates was denied by a wonderful save at the other end soon after, as Alisson tipped the ball past the post from a one-on-one.
Van Dijk flashed the ball across goal from a set piece, but nobody in a white shirt could get on the end of it.
The Dutchman was denied again late on, as Henderson produced a top save from close range to claw away a header.
The Englishman tipped Salah's header over the bar in the dying seconds too.
Forest looked to counter with Alisson out his goal following a set piece, as Johnson hit the frame of the goal from range.
Full time secured a huge win for Nottingham Forest.
The nature of the win and the fight they showed to keep a clean sheet could be massive for the rest of their campaign.
As for Liverpool, another disappointing defeat will be concerning for the Merseyside club.
Player of the match
The scorer of the vital winning goal, Taiwo Awoniyi made a huge impact on his return to Cooper's starting eleven.
He was fortunate to be in the right place at the right time to tap home early on in the second half, but his overall performance was more than deserving of the award.
The former Union Berlin striker was a nuisance for the Liverpool defence all afternoon and linked up play with the rest of the front line very effectively.
It was a hugely promising showing from the Nigerian, who have needed a goal scorer in recent weeks.