Serena Williams and Venus Williams lost in straight sets to Lucie Hradecká and Linda Nosková of the Czech Republic at the US Open on Thursday.

Serena Williams' illustrious doubles career has likely come to an end after she and her sister Venus fell in straight sets to the Czech duo of Linda Nosková and Lucie Hradecká in the first round of the US Open at Arthur Ashe Stadium in New York.

Venus Williams lost in the first round on Tuesday.

Thursday night might have been the last match for Serena and Venus as a doubles team.

The Czech Republic duo of Nosková, 17, and Hradecká, 37, advanced to the second round, winning 7-6(5), 6-4.

"I think we did a very good job, and I'm so sorry for you that we beat them, but we are so happy we did it," Hradecká said to the 23,000-plus fans in an on-court interview moments after the match.

The Williams duo started well and had two set points with a 5-4 lead in the first, but the Czechs fought back.