Rossi is readying his Hungarian troops to take on James and his Welsh team-mates on Tuesday, in their Euro 2020 qualifier.
The 54-year-old appears to have earmarked James as one of Wales key men ahead of the game, despite the youngster earning just two senior caps to date.
The winger has gleamed a reputation for his unstoppable pace in the past year, which Rossi is all to aware of. In fact, so rapid is James, he has been compared to the world’s former fastest man, Usain Bolt.
“James' speed reminds me of Usain Bolt - to be so fast like him is really incredible,” said Rossi.
“In the last years I don't remember one player that gave me this sensation. His acceleration is so peculiar, which is why Manchester United have bought him.”
It’s not just figures from the world of athletics that James has been likened to - Rossi believes he even share similar characteristics with one of the all-time greatest strikers.
"In the past I played against a very fast player who, for me, was the best after [Diego] Maradona - Ronaldo,” said the Hunger coach.
"He was just not known for speed, but for everything. His acceleration looked like James, though at the moment the skills are a little bit different.”
James capped off a remarkable 12 months on Friday, when Manchester United announced that a deal was in place to sign the winger from Swansea, just one season on from being sent back from an unsuccessful loan spell at League one side Shrewsbury Town.
However, James excelled in 2018/19 with the Swans and his five goals and 10 assists in all competitions caught the attention of a number of Premier League sides.
In the meantime, the 21-year-old will be hoping for an improvement in Wales’ fortunes on Tuesday after they lost 2-1 to Croatia at the weekend.
Ryan Giggs’ men are currently fourth in the qualification group, but are just three points behind first-place Hungary.