The Nets' starting point guard and center are out again with injuries and will not make the trip to face the Atlantic Division-leading Raptors (6-7).
Williams will miss his third straight game after spraining his left ankle again. He will sit out his fifth contest in six games. Lopez's sprained ankle will sideline him for a sixth straight game.
The Nets (3-10), who have lost eight of their last nine games, may also be without Andrei Kirilenko and Jason Terry. Kirilenko (back), Terry (knee), Lopez, Williams and Shaun Livingston (head contusion) all did not practice Monday. Livingston, though, is considered probable to play against Toronto.
Williams has played in nine games this season but has lasted a total of 18 minutes in two of the last six games due to his two left ankle injuries. He missed the majority of training camp and had to start the season on a minutes restriction due to a right ankle injury.
"It's frustrating," Williams said. "The first couple of days I was down just because it seems like I can't catch a break. It seems like I start feeling good and I just can't get into a rhythm because I can't stay on the floor.
"We're losing right now, so I really want to be out there, and I just can't do it."
Williams said his left ankle is day to day but it's even more sore than the previous left ankle injury because the ankle wasn't completely healed when he rolled it again last Wednesday.
"The problem is I sprained an ankle that was already sprained," Williams said. "It wasn't completely healed when I went back out there."
The Nets desperately need to get healthy. Coach Jason Kidd has had to use five different starting lineups. Joe Johnson is the only Net to have started every game.
"Obviously we didn't expect for Brook and Deron to be out together, two of our main pieces," Johnson said. "Man, it's definitely hurt us. But we've got to try to do something to get some wins before those guys get back. We can't wait."