In her first match after Wimbledon in San Jose a month ago, the teenager was well beaten by 49th-ranked Zhang, who boasts huge experience on the tour.
Raducanu had won 12 matches since that loss, though, including four at Flushing Meadows, and she outclassed Zhang in a 6-2 6-4 victory that was thoroughly one-sided until a late rally from the Chinese player.
“I’ve had five matches here in New York, so I feel very comfortable with the conditions and the courts,” said Raducanu.
“I’m getting more and more used to it and each round I feel I’m going for my shots more, and today I think that was evident. I think I’ve come a very long way since my first qualifying match here, but also since the first tournament of this trip five weeks ago.
“Playing at the tour level for so many weeks in a row definitely builds your confidence and I’ve been fortunate enough to win quite a few matches.”
Raducanu revealed it took her 90 minutes to travel to Flushing Meadows from Manhattan, and the match started an hour later than billed while the clean-up continued following Wednesday night’s intense storm, but all was mercifully calm in New York.
Raducanu is yet to drop a set in either qualifying or the main draw and she set her stall out straightaway with a break to love.
The teenager was superb in both attack and defence and she led by a set and 4-0 before Zhang belatedly mounted a challenge with three games in a row.
But Raducanu regrouped impressively, stopping the rot with a confident service game and showing none of the nerves that had afflicted her at the end of her first-round victory over Stefanie Voegele.
“That match meant so much to me on a personal level,” she said. “I wanted to win so, so bad.
“I knew there was going to be adversity at some point in the match and, honestly, I was 6-2 4-0 up but I was having to work so hard for every single point, and the games, they were very long and challenging.
“The scoreline was saying one thing, but the level of tennis we were both playing I think was suggesting a completely different story.
“It didn’t really bother me that she came back because I knew that she’s a great player, she’s extremely experienced, she’s going to throw everything she had at me. So I’m just very proud of myself for overcoming that and managing to close it out at the end.”
Raducanu will next take on another of 2021’s form players in Spain’s Sara Sorribes Tormo, where victory could be enough to propel her into the top 100.
The teenager already has quite a following and there was a sizeable crowd on court 10 to watch the match, after which Raducanu stayed behind to sign autographs and pose for pictures.
The end of the match was played to the backing track of a loud drumbeat coming from outside the courts, with the young British player saying: “It was quite loud but I sort of twisted my mind into thinking they were supporting me and it helped in the end.
“I’m extremely grateful for all the support I’ve been receiving here in the States. Honestly, it’s taken me a bit by surprise, but I’m so grateful for everyone who’s cheering for me.
“Of course I really want to connect with the fans and people watching because they’re doing so much for me, getting me through some really, really tight moments. Connecting with them, I have so much fun, especially the younger kids. I hope that they can get a little bit inspired.”