Parker left at halftime of the Spurs' 125-118 double-overtime victory against Washington on Wednesday because of tightness in his lower back, and coach Gregg Popovich said he wouldn't be available for Thursday's game.
As for Duncan? The 37-year-old veteran just needs some rest after playing a season-high 40 minutes against the Wizards as the Spurs continue a nine-game road trip.
Popovich joked after the victory against the Wizards that he was expecting Duncan to play 48 minutes Thursday night against the Nets.
"I am absolutely up for that," Duncan deadpanned Wednesday. "Sounds like fun."
The Associated Press contributed to this report.