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Nunez marked his return from injury by heading home in the ninth minute of stoppage-time to seal the win, which lifted his side four points clear at the top of the Premier League.

But the Uruguay international’s last-gasp effort left Forest’s players, staff and fans furious at the final whistle after referee Paul Tierney had stopped play before the build-up to Liverpool’s winner for an apparent head injury to Ibrahima Konate.

Tierney blew with Forest in possession on the edge of Liverpool’s area and after Konate had quickly recovered, the official dropped the ball to visiting goalkeeper Caoimhin Kelleher, who then started the move that led to his side’s dramatic winner.

Klopp said: “It happened exactly the same in the first half didn’t it? Exactly the same, just the other way round.

“I accepted it would happen like that because it happened in the first half. If it didn’t happen in the first half, I would have asked the question as well.

“I would assume that’s the rule, I don’t know. But because it happened twice and got handled exactly the same, I don’t really see their reasons for a discussion.”

Earlier in the game, Tierney halted a Liverpool attack after Forest skipper Ryan Yates was felled by Harvey Elliott’s shot and play resumed with home goalkeeper Matz Sels taking possession.

Nottingham Forest referee analyst Mark Clattenburg claimed Tierney made a mistake in allowing the goal to stand.

Clattenburg, appointed to his role at Forest last month, said: “The law states that, if the referee is going to stop the game – which he is entitled to for a head injury – the ball has to go back to the team that has possession. Nottingham Forest clearly had possession.

“The laws of the game clearly state that, when the referee blows his whistle, the team that has possession should get possession when the game is started again.”

Former Premier League referee Clattenburg added: “When Liverpool were given possession, they went on the attack and eventually scored from it.

“It is another decision that has gone against Nottingham Forest… We just need to hope that this luck changes.”

Clattenburg said he would speak to the referees’ governing body, the PGMOL, about the incident.

“With the relations I have with the PGMOL and the Premier League, we will discuss what has happened today and then plot what the next course of action is,” he said.

“The law is clear. When you have possession outside of the penalty area, you get possession back.

“In that crucial moment, Forest had the ball in the corner. They could have absorbed a bit of time and got the result, with the score at 0-0.”

Klopp added: “I understand 100 per cent the excitement and the anger of Nottingham, of course, they fought for everything. But it happened twice the same and was consistent.”

Nunez’s last-gasp effort secured Liverpool its first league win at The City Ground in almost 40 years and 14 matches to heap the pressure on Manchester City and Arsenal, who play on Monday (AEDT) and Tuesday (AEDT) respectively.

Klopp said it had been a huge effort from his injury-hit squad, which has registered six straight wins in all competitions, including last Monday's (AEDT) Carabao Cup final win over Chelsea.

“Four games in 11 days, come on. Five in 15,” Klopp added. “It’s really tough. With our squad situation it’s super-tough and how the boys fought through that is really special.

“The fourth game was the toughest. It was an unbelievable effort the boys put in. A proper, proper shift.

“If you had asked me 12 days ago if it was possible to win all four games, I’d have said no.”

Forest’s players and staff surrounded Tierney at the final whistle, with coach Steven Reid shown a red card, while boss Nuno Espirito Santo refused to comment on the incident after the final whistle.

Forest later dismissed reports that owner Evangelos Marinakis had chased Tierney down the tunnel.

Nuno said: “I will not comment on the referee. We played a very good game against a very good team, fantastic players and manager and we limited them.

“They had chances, we had chances, it was a good game of football. We had clear chances to do better, to improve. We should have been more clinical.

“I’m proud of the boys because they worked very hard. They combined, they helped each other, they defend the box, they did two-on-ones – they did everything. But we can improve.”