The 16-year-old has emerged as one of the best young strikers at youth level in England, scoring 32 goals in 18 matches for the Under-18s, which included 10 in a one game against Liverpool.
Arsenal had held extensive talks with Obi-Martin over a new contract but Mikel Arteta’s side faced strong competition with several clubs interested.
But Obi-Martin has opted to leave Arsenal and it’s understood that he has now reached an agreement to join United.
It has been reported that Obi-Martin has opted to make the move to Old Trafford after being convinced of a clear pathway to the first team.
Meanwhile, Fabrizio Romano reports that Van Nistelrooy also played a major role in United’s push to sign Obi-Martin as he personally spoke with the striker about the club’s development plan.
Van Nistelrooy, who scored 150 goals in 219 appearances for United, returned to Old Trafford this summer as part of Erik ten Hag’s new-look coaching set-up.
The 48-year-old has been quick to make an impact since returning to United, with goalkeeper Tom Heaton impressed by the Dutchman’s ‘eye for detail’.
‘I’ve come up against quite a few players in my time and he’s the best finisher I’ve ever seen,’ Heaton said.
‘It was so good to see him back at the club, I have to say.
‘He’s been brilliant. His level of detail is superb. You’d be forgiven for thinking: ‘He’s a United legend coming in, is he just a face for it?’ But his level of detail – I’ve been in a couple of meetings – has been outstanding, Rene as well.’
United defender Jonny Evans also echoed Heaton’s verdict on Van Nistelrooy.
‘Having Ruud come back has been great, especially for myself. I sort of grew up idolising Ruud and the way he used to play,’ Evans said.
‘I got a little bit of a chance when I was a youth team player to see him. When he was coming to the end of his United career I might have trained with him once or twice when he was returning from injury.
‘It is good to have someone of that calibre and respect in the squad.’
For more stories like this, check our sport page.
Follow Metro Sport for the latest news on
Facebook, Twitter and Instagram.
MORE : Arsenal star reveals how he convinced Riccardo Calafiori to sign for the Gunners
MORE : Arsenal believe young star is set to enjoy ‘breakthrough season’
MORE : Manchester United dealt Jarrad Branthwaite blow despite Everton signing potential replacement
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.