James curled home on 17 minutes to give Wales the 1-0 win in Cardiff, and Giggs – also a former Wales international and United winger – expressed his delight in the young player’s performance.
“He’s one of those players, you know what he’s going to do, but you can’t stop it,” Giggs said.
“There are so many goals (he’s scored) like that. He can go either way.
“Early on when I saw DJ, just like any young winger, there can be that improvement in the final ball and scoring more goals, but he’s doing that.
“To do what he’s done at the start of the season is amazing.”
James, who signed for United from Championship side Swansea this summer for £15 million, has scored three times for United in four appearances, and his impressive finish on Monday marked his second for his country. His first came against Slovakia in his international debut in March, and was also a winning goal.
“The next step obviously is that consistency, which he’s shown so far and he needs to carry on," Giggs said.
“But I’ve got no doubts that will happen because he wants to be the best.”
James’ performance against Belarus was particularly important as Wales were without Juventus midfielder Aaron Ramsey and Bournemouth forward David Brooks.
Brooks is expected to be absent for a prolonged period after undergoing knee surgery, but Giggs said he was hopeful that Ramsey would soon make his first appearance in Wales’ Euro 2020 qualifying campaign, once he has overcome a hamstring issue.
Wales were handed a boost in their qualifying hopes on Monday as fellow Group E teams Croatia and Hungary dropped points – the former drawing 1-1 with bottom-placed Azerbaijan, while second-placed Hungary suffered defeat to Slovakia.
Wales sit four points behind Croatia and three behind Hungary and Slovakia with a game in hand on all of those teams.
“I don’t think they’re the worst results in the world,” said Giggs, whose team play Slovakia and Croatia in October.
“It was a difficult one with Hungary and Slovakia. We definitely didn’t want a Hungary win.
“But we’ve got to focus on ourselves. It’s still in our hands.”
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