Reigning US Open singles champion Emma Raducanu was embarrassed in her first professional doubles match in Washington on Monday.

The British No. 1 and fellow Danish teenager Clara Tauson were beaten in the first round of the Citi Open by Romanian veteran Monica Niculescu and her Czech partner Lucie Hradecka 6-4, 6-1.

Raducanu will shift her attention to the women’s singles event today, where she will face American qualifier Louisa Chirico.

Venus Williams lost 4-6, 6-1, 6-4 to Canadian Rebecca Marino on her return to singles after over a year out.

In other matches Jessica Pegula and Simona Halep both advanced, Pegula beat fellow American Hailey Baptiste 6-2, 6-2. Halep defeated Cristina Bucsa of Spain 6-3, 7-5.

“I had a good run in Wimbledon, so it’s always tough to start,” Halep said. “But I’m really happy I won the match and I can play another match here.”