National Hockey League superstar Sidney Crosby, who has played only eight games since returning from a 10-month layoff after a concussion, is back off the ice indefinitely. The 24-year-old Pittsburgh Penguins center said Monday that he has suffered a return of the problems that nagged him earlier this year after two blows to the head in early January brought on concussion symptoms. "I'm not happy about watching, but I have to make sure with these sort of things that I'm careful and making sure I'm 100 percent before coming back," Crosby said. "This is something I have to be careful with." There is no timetable for the Canadian playmaker to return to the Penguins' lineup. He sat out a two-game road trip to Philadelphia and New York last weekend as a precaution but felt concussion symptoms during weekend workouts. Crosby has become the NHL's signature player, leading the Penguins to the 2009 Stanley Cup, and became a Canadian hero after scoring the golden goal in over-time to win the Winter Olympic crown for Canada last year at Vancouver. Crosby, who definitely will not play on Tuesday against Detroit, said a test showed he had less trouble than what he had been suffering last season. "I did my test and it went pretty good. That was a good sign," Crosby said. "It's much different than previously going through that stuff. That was encouraging." "I skated the following day after with exertion. I just didn't feel right. After talking with everyone I figured it was better to be cautious and not take any chances. That's where I'm at right now." Crosby, who scored twice in his return game November 23 against the New York Islanders, has not netted a goal since but has helped set up 10 other goals. Crosby hopes he is not in for another long rehabilitation before returning to the Pittsburgh lineup. "I've been doing light exertion stuff and seeing how that goes," Crosby said. "It's that whole (recovery) routine again, but hopefully not as long. When I wasn't doing something for six or seven months, that process was a little longer. Hopefully, that's not the case here."