Huub Stevens has claimed that Stuttgart's performance was a "joke" after his side were held to a goalless draw by SC Paderborn on Saturday.
Another below-par display left Stuttgart just three points off the bottom of the table heading into the winter break, and Stevens has suggested that he may have to change his approach to get a reaction from his players.
"The way we played was a joke. There are a few players here who have not realised yet that we are in a relegation battle," Stevens told reporters.
"Maybe I'm going to have to get tougher with them. We wanted to put on a show, but the first thing you need is to be aggressive.
"We weren't and I cannot accept that. It's no coincidence we're as low as we are in the table."
Stuttgart return from the winter break to host Borussia Monchengladbach on January 31.