Wood's header means he is now Forest's record Premier League scorer, overtaking Bryan Roy by moving to 25 in the competition.
The New Zealand forward has certainly struck up a positive working relationship with manager Nuno Espirito Santo, taking his tally to 21 goals in 31 Premier League appearances under the Portuguese, including 13 in 16 matches away from the City Ground.
"He's doing amazing. We're so glad to have him. It's never too late," Nuno told Match of the Day after the win.
He might have been able to celebrate his 33rd birthday even earlier in the game, but Wood was caught by surprise when Ola Aina's cross reached him at the far post and he stabbed wide.
Yet Wood is having a superb season. Only superstar duo Mohamed Salah and Erling Haaland are ahead of him in the Premier League scoring stakes. And, having left Manchester City empty-handed on Wednesday after firing wide when he ran on to Kevin de Bruyne's wayward backpass, he was not going to return without reward from a second visit to the city.
Major question marks will be asked of United's defence, with Onana, De Ligt and Martinez all having an opportunity to deal with Wood's header but failing to prevent it finding the net.
The outcome from a United perspective was sadly predictable but for Forest, after their own patchy run of one win in four games, it was a welcome return to form that was celebrated long and loud by their travelling support at the final whistle.
They had not won against United at Old Trafford since 17 December 1994 when Stan Collymore and Stuart Pearce scored their goals.