Oli McBurnie told Dan James not to turn down Manchester United and urged him to go there and become a "superstar" before completing his £25m switch from Swansea.
The former United and current Swansea winger formed a formidable link with James at the Championship club last season and believes the young Wales international has everything it takes to be a success at Old Trafford.
McBurnie, who played for United at the 2013 Milk Cup before signing for Bradford City, told ManUtd.com: "I don't think many are hungrier than DJ. He's got such inner self-confidence and belief in himself.
"He just wants to get as high as possible and go as far as he can. When he was in the first team at Swansea, he played a couple of games but the gaffer pulled him out and he was kind of like asking 'why?'
"The gaffer said 'I just want to protect you' but he was saying 'no, I just want to play as much as I can and want to keep going'. He is hungry to play on the biggest stage and that's why United are the perfect club to go to.
"He was asking me what United is like and a lot of things, as I know some of the boys there and I am still in contact with them. He was asking me what I thought, but his mind was already made up - 100 per cent he wanted to go there.
"The advice I gave him, anyway, was 'United? You can never turn down that club. Go there and make yourself a superstar'.
"That is what he's got to do and I'm sure United fans will see what he's all about. He's electric and the sort of boy who gets fans on their feet and a player all fans want to go to watch."
James became United's first signing under new manager Ole Gunnar Solskjaer, who is targeting young English talent this summer, and they have now moved for the Crystal Palace right-back Aaron Wan-Bissaka.
United also want to sign Leicester centre-back Harry Maguire and Newcastle midfielder Sean Longstaff, Sky Sports News understands, while they have also made an enquiry about Fulham's Ryan Sessegnon, who prefers a move to Tottenham.