Manchester United forward Rashford, 20, is in Gareth Southgate's squad with club team-mate Young, for the tournament which begins 14 July.
England's players have been training together at St George's Park over the past week, with their first pre-World Cup friendly coming against Nigeria on Saturday evening.
"I've said it since I saw him in the youth team; he has a massive future ahead of him".
Young, who has been selected in the England squad for next months tournament despite spending several year in the global wilderness, is backing Rashford to have a major impact for his country.
Young, though, is adamant they are not there merely to make up the numbers, as he prepares to participate in his first World Cup at the age of 33.
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Kane has scored 13 goals in 24 worldwide appearances and said: "My game has always been about putting the team first". After the goal, England lost its collective mind, as you would expect.
Rashford has scored twice in 17 appearances so far for England and Young added: 'If you look at the goals he has scored on how many different debuts, it shows he steps up in big games.
And Young is aware of the need for Southgate's squad to be on their guard when they go up against Tunisia, Panama and Belgium in Group G. He's very comfortable with who he is and I think he should be - he is a fantastic young boy and a great player.
In his time away from England, he has adapted to a change in role after switching from winger to wing-back at Old Trafford.
"I wasn't in squads, but I said before that I never gave up hope of getting back into England squads. I would rather be in the attacking half than defending".
The Three Lions aren't expected to go too far in the tournament given their youthful squad but the Red Devil insists he has a good feeling.
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In Brazil, Low had options in midfield, including Lahm, who had been converted into a central midfielder by Pep at Bayern. If anything, the scoreline might have flattered Germany as Mexico wasted a number of fine chances on the counter.
"A lot of people say he has to take it out of his game, but I think he's one of those players that plays on the edge".
"Whether it's going to happen, whether you are on the pitch, I'm not sure how you react to it", he said.
"Going into the tournament, we're full of confidence, especially with the friendlies we've played against some of the best teams in the world".
"Different managers play different formations".
"When we eventually get out to Russian Federation, the togetherness and team spirit we have shown so far will take us a long way in the tournament".
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None of those laws or precedents mean that children must be taken away from their parents. Trump "doesn't like this, but he also understands it's the law of the land", he added.