Serena congratulates fellow Americans Keys, Stephens on first US Open final

NEW YORK, NY, USA - Ahead of the highly-anticipated all-American US Open women's final between Madison Keys and Sloane Stephens, 23-time Grand Slam champion Serena Williams extended her congratulations to her compatriots in a series of tweets sent out on Friday evening.

Serena has been out of action since January, when she broke the Open Era record for Grand Slam titles won at the Australian Open, expecting the birth of her first child.

Keys and Stephens each advanced into their maiden Grand Slam finals after winning their respective all-American semifinals over CoCo Vandeweghe and Serena's sister Venus Williams on Thursday.

Check out Serena's tweets here: