Wood treble gives Nuno first win as Forest boss
Wood left Newcastle to join Forest in a £15 million ($19 million) deal in June, but had scored only four times for his new club.
Nuno Espirito Santo clinched his first win in charge of Nottingham Forest as Chris Wood's hat-trick against his former club Newcastle inspired a 3-1 victory, while Liverpool will go top of the Premier League if they avoid defeat at Burnley later on Tuesday.
Wood left Newcastle to join Forest in a £15 million ($19 million) deal in June, but had scored only four times for his new club.
The 32-year-old New Zealand international managed just two league goals for Newcastle last term, but he surpassed that meagre total with a treble in 60 minutes at St James' Park.
Alexander Isak's first half penalty put Newcastle ahead, but Wood equalised just before the break.
He struck twice more in the second half to give former Tottenham manager Nuno his maiden victory with Forest in his second game in charge after replacing the sacked Steve Cooper.
It was Forest's first win in eight games and only their second success in their last 15 matches.
Forest moved five points clear of the relegation zone ahead of the rest of the day's matches.
Newcastle's fifth defeat in their last seven games in all competitions leaves them seven points adrift of the top four in seventh place.
Nuno's first game in charge ended in a painful 3-2 stoppage-time defeat against Bournemouth at the City Ground last weekend.
Morgan Gibbs-White fired narrowly wide in the opening minutes as Forest tried to erase the bitter taste from Nuno's first game.
But Newcastle took the lead in the 23rd minute when Sweden striker Isak was tripped in the area by Ola Aina.
Isak picked himself up to squeeze the penalty past Matt Turner for his 10th goal this season.
Anthony Elanga wasted two good chances to equalise when he fired into the side-netting and shot straight at Newcastle keeper Martin Dubravka moments later when a pass to the unmarked Wood looked the better option.
Forest kept battling and Dan Burn's goalbound effort was scrambled away by the visitors' defence before they equalised in first half stoppage-time.
Making amends for his earlier mistake, Elanga was the provider as he took Gibbs-White's pass and cut back a low cross that Wood finished from close-range.
Isak should have restored Newcastle's advantage seconds later, but his header lacked the power to beat Turner.
Gibbs-White nodded inches past the post immediately after the interval.
In keeping with their lively opening to the second half, Forest snatched the lead in the 53rd minute.
Elanga was the catalyst again with a superb through-ball and Wood did the rest, twisting and turning until he had space to guide a cool finish past Dubravka.
Wood was in the mood and he completed his hat-trick on the hour, surging onto Murillo's pass and slaloming around Dubravka to slot home.
Later on Boxing Day, second placed Liverpool will climb above leaders Arsenal with a draw or win against second bottom Burnley.
Third placed Aston Villa will aim to step up their unexpected title challenge with a victory at troubled Manchester United.
In the day's other matches, Sheffield United face fellow strugglers Luton and Bournemouth host Fulham.