Darwin Núñez headed in a last-gasp winner as Premier League leaders Liverpool snatched three points with a wild 1-0 victory over relegation-threatened Nottingham Forest at the City Ground on Saturday.

Núñez's 99th-minute goal put Liverpool four points clear of second-placed Manchester City with 63 points from 27 matches -- although Pep Guardiola's side have a game in hand. The result left a shattered Forest four points above the relegation zone in 17th.

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"Most difficult game we played because of the circumstances," Liverpool manager Jurgen Klopp said. "Four games in 11 days is really tricky with the squad situation we have.

"It was super special. You could see it didn't go easy for us today in any part of the game. It's so hard. Wonderful feeling. I'm really happy. I can't ask for more than what the boys are doing."

There was bedlam after the final whistle with referee Paul Tierney surrounded by Forest's enraged coaching staff, with first-team coach Steven Reid being shown a red card.

Liverpool dominated possession, but struggled in the final third against Forest's diligent defensive effort and the game looked destined for a draw.

Liverpool continued to press with Forest goalkeeper Matz Sels making some terrific late stop including a brilliant diving save of a Núñez header minutes before xthe substitute's late heroics on Alexis Mac Allister's cross that had the Liverpool bench leaping to their feet in celebration.

"In that moment I knew it was last minute and I just had to put it in," Mac Allister said. "Darwin is such an important player for us. There is no easy game in the Premier League. Very happy, very happy."

Klopp praised Mac Allister's poise.

"The goal was set up by a guy who was the calmest on the whole pitch," he said. "He was calm. He chips the ball there. Super assist and super important goal."

Liverpool's hectic 11 days included a league win over Luton Town, a fifth-round FA Cup win over Southampton, and a victory over Chelsea in the Carabao Cup final.

Klopp has also wrestled with an injury crisis that has sidelined key players including talisman Mohamed Salah -- who sat out again Sunday with a hamstring injury -- forcing him to plug holes with young players.

"If you'd told me 12 days ago we would win all four games I would have said no chance, it was impossible," Klopp said. "In the circumstances winning the games is ridiculous."

Substitutes Núñez and Dominik Szoboszlai returned from injury on Saturday, and their impact was immediately felt.