The 18-year-old went into the New York Grand Slam surrounded by intrigue after surprising everyone with a run to the fourth round at Wimbledon earlier in the summer.
But no-one expected Raducanu, now ranked 23rd in the world, would become the first ever qualifier to win the tournament, let alone do so without dropping a single set to any opponent across all 10 matches.
Henman, a six-time Grand Slam semi-finalist during his playing days, says he’s been involved in the sport long enough to know whether or not someone is the real deal.
“What’s been astonishing is how she’s taken it in her stride, at 18 years of age,” he told Radio Four’s Today programme.
“The level of tennis she’s played – she’s won 10 matches to win the US Open – it’s absolutely incredible.
“Pressure is all self inflicted, but she’s handled herself so well and that’s what’s so incredibly exciting for her moving forward, but also very exciting for us because we can follow that journey.
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“For British tennis, British sport and for world tennis it’s really changed the landscape in the last three weeks.
“I’ve been around the game long enough to know who’s good, who’s very good, and who could be a flash in the pan, and that could not be further from the truth.
“She’s the real deal, and she’s going to win more of these events in the future, I’m convinced. She’s going to be a superstar in this sport and an incredible role model for young girls and young children.”
While working as a pundit for Amazon Prime Video’s coverage of the tournament at Flushing Meadows, Henman became something of a talisman for Raducanu on the court and would regularly chat with the teenager before and after matches.
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After her ace to win match point against Leylah Fernandez in the final and her initial drop to the floor in disbelief of what she had achieved, the first thing the Briton did was look for him at the side of the court and give him a big beaming smile.
Henman has played down his role in her success, though, and did not want to take away from what the teenager has achieved.
“I’ve done very little. I’ve been courtside cheerleader – I think is about the maximum,” he said.
“But I feel very lucky to be part of the Prime team here in New York and therefore I’ve been courtside for every match, the best seat in the house, to see her and the way she has played and this fairytale run.
“And fairytale runs don’t always end with a victory and that’s what’s happened. I think I’m still slightly in shock so I dread to think how she feels.”
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