Before leading Washington to a 93-80 win, Toliver read a statement condemning the Unite the Right rally happening near the White House.
Elena Delle Donne leads four starters in double figures as Washington closes in on playoff bye.
U.S. Open will be first Grand Slam to implement on-court clock to keep matches on pace.
The 21-year-old perseveres through a grueling week to become the first repeat champion since Juan Martin del Potro in 2008 and 2009. He beat Alex de Minaur, 6-2, 6-4, in the final.
Zverev, 21, beats 19-year-old Stefanos Tsitsipas, 6-2, 6-4, to move within a match of his second straight Citi Open title. He will face Australia native Alex de Minaur on Sunday.
Washington's hard-court classic has dealt with weather delays every day this week, and Murray didn't get on court until Thursday night turned into Friday morning.
Unseeded Andy Murray advances at 3:02 a.m. Friday, faces a quarterfinal later in the day.
“It’s definitely not just another match for both of us,” top-seeded Alexander Zverev said.
No. 3 seed Naomi Osaka is now the highest-ranked woman left in the event after Stephens lost to Andrea Petkovic, and Caroline Wozniacki withdrew Tuesday.
The 21-year-old will be the highest-paid player in the history of the recently beleaguered franchise.