U.S. Open champ Emma Raducanu bounced from Transylvania Open in straight sets by Marta Kostyuk

Emma Raducanu became arguably the new face of women's tennis this year following her unexpected run at Wimbledon and her U.S. Open triumph, but it was a different teenager who cut her Transylvania Open experience short.

As Sky Sports noted, 19-year-old Ukrainian Marta Kostyuk toppled Raducanu, 18, 6-2, 6-1 in the Transylvania Open quarterfinals on Friday. Kostyuk needed just 57 minutes to get past the British No. 1 and world No. 23 to set up a clash with Simona Halep, the tournament's top seed. 

The Transylvania Open is being held in Romania, the home country of Raducanu's father and where her grandmother lives. Raducanu earned her first WTA Tour victory when she beat Polona Hercog 4-6, 7-5, 6-1 on Tuesday. 

"Honestly I don't know how I won the first game," Kostyuk said after her win, according to BBC Sport. "I was 15-40 down, she had advantage, she was serving, and I think that's where everything started - I somehow won that game and I gained this confidence."

The BBC added Raducanu committed 41 unforced errors in the defeat. She will now continue her search for a new coach after she parted ways with Andrew Richardson last month.