Warsofsky will play in his fifth NHL game when the Bruins (36-16-3) face the St. Louis Blues (37-12-6) at Scottrade Center.
The Bruins will be without Chara for the final two games leading up to the 2014 Sochi Olympics because the Bruins captain and 2009 Norris Trophy winner has left for Russia and will be the flag bearer for Slovakia at the opening ceremony Friday.
"I don't think I can play that high, how many minutes he usually plays," Warsofsky said of Chara, who averages 24:57 of ice time per game. "I just want to play my game. The whole [defense] corps will have to step up. I'm looking forward to it."
Warsofsky was selected by the Blues in the fourth round (No. 95) of the 2008 NHL Draft. Warsofsky, who grew up 30 miles south of Boston, was traded to the Bruins in 2010 for forward Vladimir Sobotka.
"I was still in college. At the time I hadn't played in any professional games, so that wasn't a big deal to me," said Warsofsky, who has one goal in four games with the Bruins. "Obviously I got traded to my hometown organization. For me, that was a special opportunity.
"You never want to get traded from any team, but for me to get traded to Boston and have an opportunity to play [Thursday], it's a good feeling."
Bruins coach Claude Julien said the responsibility to replace Chara doesn't fall on one player.
"I think the responsibility lies on everybody that's out there," Julien said. "Everybody has to do their job. You just can't expect a player to say, 'I'm going to pick up the slack.' They may get more ice time. That may be what's expected. … To expect someone to give more is unrealistic.
"We're going to try and manage it as best as we can, but at the same time you've got to rely on those guys to do a job. It's as simple as that. It's not about putting pressure on [Warsofsky], it's about letting them know they've got to go out there and play their game. If they're here we've got confidence in them to play well."
The Blues will be without Sobotka, who is out a minimum of four weeks with a broken kneecap, and may be without Vladimir Tarasenko, who coach Ken Hitchcock said is dealing with an illness for the second time in two weeks. Dmitrij Jaskin is expected to replace Tarasenko in the lineup.
"Jaskin will go in, Tarasenko has got flu-like symptoms so he was left at home. I don't think he'll play [Thursday]," Hitchcock said. "… We haven't lost Tarasenko yet. He's still got the rest of the day, but we like Jaskin. He's a good player for us. He's come up, made a good account for himself."
Here are the projected lineups: