Per USA Today's Mark Medina, both players have been ruled out for the second consecutive game.
Williams is still serving his NBA-mandated 10-day self-quarantine after he was photographed at an Atlanta strip club last week while away from the Clippers with an excused absence.
His self-quarantine began on Sunday (July 26), meaning the earliest Williams will be eligible to play is the Clippers' Aug. 6 game against the Dallas Mavericks.
ESPN's Ohm Youngmisuk reported Harrell left the Clippers on July 17 due to a family emergency.
"Things happen in our lives, so we've just got to leave it there," head coach Doc Rivers told reporters about Harrell's absence, via Youngmisuk. "It's obviously a personal matter at home that he did need to go to. So we're just going to wait for him. Like when he needs to get back, he'll be back."
On Tuesday, Yahoo Sports' Chris Haynes reported it's unclear when Harrell will return to the NBA campus in Lake Buena Vista, Florida. Youngmisuk reported Friday Harrell is still listed as "not with the team."
Haynes did note Harrell has "tested negative for COVID-19 each day he has been away." As long as that remains the case, the 26-year-old will only have to go through a mandatory four-day self-quarantine if or when he returns to the campus.
The Clippers (44-21) lost 103-101 to the Los Angeles Lakers (50-14) on Thursday in the first game of the restart for both teams.