Just the news the Pittsburgh Penguins dreaded — Sidney Crosby is back on the sidelines.

Only this time, the Penguins insist their superstar will miss two games strictly for precautionary reasons and not because of a recurrence of the concussion that forced him to sit out 61 games over two seasons.

Crosby took part in a full practice Wednesday, but did not accompany the Penguins on a road trip for games Thursday at Philadelphia and Saturday at the New York Islanders. The next time he could play would be Tuesday at home against Detroit.

A hard hit in the Penguins' 3-1 loss Monday to Boston — the team did not specify which one it was — led to the decision to sit Crosby again.

Crosby and teammate Chris Kunitz collided knee-on-knee in at mid-ice during the third period, and Crosby went to the bench doubled over in pain. But he returned after several minutes, and said afterward it felt "like a stinger" — a hard hit that temporarily causes numbness.

The Penguins did not confirm that was the hit in question. Earlier in the game, Crosby was seen with what appeared to be redness on his face, possibly the result of another hit.

"Sidney took a hard hit during our game against Boston [on] Monday night and wasn't feeling 100 per cent," Penguins general manager Ray Shero said in the statement issued late Wednesday afternoon. "He saw Dr. Mickey Collins of UPMC today and took an ImPACT [neurocognitive] test, which showed no problems. However, we all think it's best that he sits out the next two games as a precaution."

The ImPACT test — designed by Pittsburgh-based researchers, including Collins — measures a person's cognitive and memory skills before and after a concussion. The test is widely used by multiple pro sports leagues and teams to determine when a player is ready to return to game action.

Crosby was administered the test periodically while he was sidelined with a concussion from Jan. 6 until Nov. 20 — one that resulted from hard hits in successive games Jan. 1 and 5.

The NHL's marquee star returned with a characteristic burst Nov. 21 against the Islanders, scoring two goals and getting four points. He went on to play in eight consecutive games, getting two goals and 10 assists for 12 points, although he didn't score a goal in any of the final seven.

The Penguins went into Wednesday's games with an Eastern Conference-leading 36 points, despite experiencing an abundance of injuries. Defencemen Kris Letang, who was being mentioned in the early Norris Trophy talk, has been out with a broken nose and a concussion since Nov. 26.

Letang was hurt on a hit by the Montreal Canadiens' Max Pacioretty, who subsequently drew a three-game suspension. Letang was not initially diagnosed with a concussion, and returned to score the game-winning goal in overtime.

Fellow defenceman Zbynek Michalek also has been out since that date with a concussion — he previously was sidelined for a month with a broken finger — and forward Tyler Kennedy also didn't playfor about a month with a concussion. Defenceman Brooks Orpik sat out the first two weeks of the season with a sports hernia.

Throughout Crosby's absence, the Penguins repeated that they would not bring him back until there were no concussion-related symptoms. This cautiousness may be reflected in their current decision to keep him out, even though there is no sign that Crosby has had any kind of setback, and by the Letang concussion that wasn't diagnosed until days later.

Crosby did not practise Tuesday, but participated in the full workout Wednesday before talking with reporters, telling them he was looking forward to Pittsburgh's first game against the rival Flyers this season.

"I think we always know it's going to be a tough game and both teams bring out the best in each other," Crosby said. "I think you just prepare for their best game."

Coach Dan Bylsma also gave no indication during his post-practice interview that Crosby might not play. The Flyers and Penguins don't meet again until Dec. 29 in Pittsburgh.