Serena Williams and Ons Jabeur defeated Shuko Aoyama and Chan Hao-ching in the quarter-finals of the doubles competition.
The American great, playing just her second match in a year, produced a strong serving performance in her win.
They saved all of the break points.
Williams said that Ons was so good that she was holding her up.
Williams joined forces with the world number three to get some grass-court practice after being granted a singles wild card into Wimbledon.
The two have shown a lot of power and deft touch at the net while playing together.
Williams said that they played better today than they did yesterday.
During the match, I looked at Ons.
Williams was asked if she would team up with her for the US Open. We played well.
They will face Serbia's Krunic and Poland's Linette in the semifinals.
Williams had doubts about her return to the tour after she injured her ankle at Wimbledon.
'Onserena' - the nickname given to the two by Williams - began strongly, with Williams showing little rust despite playing back-to-back matches for the first time in more than a year.
The two did not face a break point in the opening set and went on to win the set.
When they faced two break points on the Williams serve, the American did what she's done many times before - she sent down three ace and held.
At the changeover, Williams checked a rule with the umpire about tipping the ball over the net to make sure it wasn't a mistake.
On the whole, Williams served well and came out the better of the two on several baseline exchanges.
When asked what she did to celebrate their victory, Williams joked: "I went to the beach and for a swim like everyone else here in the cold water."
I played with my baby. She is great.