By Andy Dunn Jurgen Klopp claimed last-gasp hero Darwin Nunez was fired up by abusive chants from Nottingham Forest fans as Liverpool opened up a four-point lead at the top of the Premier League table. Nunez headed in a 99th minute winner after coming on during the second half of a controversial clash at the City Ground. And the home supporters taunted the Uruguayan by singing: “You’re just a s*** Andy Carroll.” “It was a great response to the song,” smiled Klopp. “They can sing it more often.” But even Klopp admitted Liverpool’s current winning run is defying logic as they continue to defy an…