In one exchange with Bloomberg, Warren pressed the former New York mayor so much that some in the crowd began jeering the Massachusetts Senator.
As the debate began, Warren made the case that she was the better progressive choice than Sanders, but did not try to tear down the Independent Senator from Vermont.
"Bernie and I agree on a lot of things, but I think I would make a better president than Bernie," Warren said.
"Progressives have got one shot. And we need to spend it with a leader who will get something done," Warren added, as the closest she came to criticizing Sanders directly came as she accused Sanders aides of attacking her.
"And then Bernie's team trashed me for it," Warren said.
But after that - it was almost all about Bloomberg.
The polls in South Carolina have not shown much in the way of promise for Warren, as she's been mired in a battle for fourth place with Pete Buttigieg, well behind Joe Biden, Sanders, and Tom Steyer.