Konjah, who three years ago reigned as the Australian Open and U.S. Open junior champion, has been slowed by wrist and ankle injuries and a stress fracture in her back, and shown only glimpses of her vast potential in WTA Tour tennis.
But the world number 92 had a coming out party in the round of 16, with a 6-4 6-4 upset of fourth seed Agnieszka Radwanska that made her the first Croatian woman to reach the last eight at Flushing Meadows.
"The type of tennis she played last night, she could be something special," Mary Joe Fernandez, the U.S. Fed Cup captain and ESPN pundit, told Reuters on Tuesday.
Her ESPN colleague Pam Shriver, winner of 21 singles titles and 21 grand slam doubles crowns, agreed.
"We were really impressed by her power quotient and mixing in some drop shots. And her serve," she enthused.
"At 18 she has one of the best teenage serves that I've seen since Venus and Serena (Williams) came up. She was hitting many serves at 115, 120 miles per hour."
Standing between Konjuh and the semi-finals is 10th seed Karolina Pliskova of the Czech Republic.
"This next one will be a big one for her and for Pliskova, she's playing her first quarter-final, too. You have two first-timers in that stage of a major, so nerves is a big factor," Fernandez said.
"Similar game styles with big first serves. They're going to be going for anything. Konjah moves a little bit better than Pliskova but if she wins that, whew!"
Time will tell but both Shriver and Fernandez said it was exciting to see a young player assert herself.
It was once commonplace for a rising youngster with nothing to lose to make a grand slam splash, said Shriver.
"That's the way it used to be so often, the teenager would feel no pressure and be able to play their best tennis and we've lost that aspect the last decade, 15 years.
"To kind of have that back is fun."
(Editing by Ian Ransom)
