Datsyuk will miss 4-5 weeks with a second-degree separation of his right shoulder, Red Wings general manager Ken Holland told MLive.com Wednesday.
The veteran was hurt during a Monday night exhibition game after he was hit by Pittsburgh Penguins defenceman Rob Scuderi.
Knee problems also caused Datsyuk to miss 47 games last season.
Stepan fractured his fibula in an on-ice workout on Wednesday, according to the team.
"We're going to know exactly this afternoon," Rangers coach Alain Vigneault said, according to NHL.com. "He was feeling real good the last 48 hours. He came in this morning, had a third X-ray done. Everything looked normal and good to go, stepped on the ice and unfortunately he got hurt. Normally, a broken leg is four to six [weeks]."