Impact of Williams sisters on display as U.S. Open women's semifinals goes all-American

NEW YORK -- When CoCo Vandeweghe and Madison Keys won their matches Wednesday night, American tennis declared victory.

That's because Vandeweghe and Keys joined Venus Williams and Sloan Stephens to make the U.S. Open semifinals an all-American affair. 

The last time that happened was in 1981, when players like Martina Navratilova and Chris Evert dominated women's tennis. 

"I really feel that this success of the Americans right now is largely due to Serena and Venus Williams and the impact that they have had on the sport and on young girls," Evert said.

United States Tennis Association CEO and Chair Katrina Adams said the semifinal milestone is serving notice that the American game is back.  

"To know we have the next crop, the next generation if you will, that are under 25, that can perhaps be at the top of their games in the next 5 to 10 years -- that's huge for us because we want our kids to get into the sport," Adams said.

And there's another headline at this year's U.S. Open: three of the four women in the semifinals are women of color, and that's never happened before.

One of those emerging stars, Stephens, was just four years old when her opponent Thursday night, Venus Williams, debuted here as a 17-year-old back in 1997.

"It's extremely important for youth to see people that look like them in the game that look like them walk or talk like then and say, 'Hey I can do that, too,'" Adams said.

Which could mean the best is yet to come.