Simona Halep of Romania continued to lead the Women's Tennis Association rankings.
Sloane Stephens beat Jelena Ostapenko 7-6 (7/5), 6-1 to lift the Miami Open title for the first time.
Sloane Stephens will enter the top 10 for the first time next week when the WTA rankings are announced.
The United States duo of Shelby Rogers and CoCo Vandeweghe beat Belarusian duo Aryna Sabalenka and Aliaksandra Sasnovich to clinch Fed Cup crown for the 18th time.
CoCo Vandeweghe, this season's Australian Open and US Open semi-finalist, ranked 10th in the world, fired 12 aces to win the match against Aryna Sabalenka of Belarus.
CoCo Vandeweghe won her Fed Cup match 6-4, 6-4, in one hour 27 minutes her first ever meeting with the 23-year-old Aliaksandra Sasnovich.
The United States Fed Cup team is made up of world number 10 CoCo Vandeweghe, US Open champion Sloane Stephens, Shelby Rogers and Alison Riske.
Garbine Muguruza officially became world number one for the first time on Monday.
Stephens, who won only $310,000 this year after being sidelined for 11 months until July by a left foot injury, said her desire for more major titles was definitely fueled.
Former world number 1 and 23-time Grand Slam champion Serena Williams made her first public comments since giving birth to a daughter one week ago
Venus Williams, a seven-time major champion, was seeking her first grand slam title since 2008
US ninth seed Williams, seeking her third US Open crown, advanced to a Thursday matchup for a spot in Saturday's final against 83rd-ranked compatriot Sloane Stephens.
With the world's dominant player Serena Williams missing for so much of the season, 16 different women have already lifted WTA titles this year with Sloane Stephens, Victoria Azarenka and Angelique Kerber the only multiple winners.
Venus Williams overcame a shaky start that left her trailing in the first set while Sloane Stephens was down 4-0 in the second but the Americans still managed to beat their Polish opponents in straight sets in the Fed Cup first round matches.
World No. 30 Sloane Stephens defeated world No. 50 Julia Goerges 7-5, 6-2 to win the Auckland Classic title
On court interviews are not new to tennis but in her opening round match at US Open 2015, Coco Vandeweghe caused a stir by speaking to a TV presenter between her match against Sloane Stephens.
Sloane Stephens defeated Venus Williams to knock her out of French Open. The young American showcased good talent against her much older compatriot.
Serena Williams hasn't been beaten in the Spanish capital since 2010 and was never troubled by her fellow American as she booked her place in the last 16 in under an hour on court.