Crosby practiced Wednesday, two days after being diagnosed, but was ruled out for the game by coach Mike Sullivan, who said the forward is making progress.

CRANBERRY, Pa. -- Captain Sidney Crosby will not play when the Pittsbugh Penguins open their season against the Washington Capitals at PPG Paints Arena on Thursday (8 p.m. ET; NBCSN, TVA Sports 2) because of a concussion.

"He's obviously feeling well enough that he wants to join the team for practice and get involved in some of the flow drills," Sullivan said. "We'll take it step by step and we're following the guidance of our medical team, and we'll go from there."

Crosby, 29, said he was disappointed but would not rush his return. The Penguins will raise their Stanley Cup championship banner prior to the game.

"It's a game you want to be a part of, but at the same time, I think I've spent more than enough time with being in this situation," Crosby said. "So I think you understand you have to be patient and you have to make sure you listen to your body. If you're ready, you're ready. If not, you don't take any chances."

Crosby was cautiously optimistic.

"I'm always happy when I'm on the ice. I'm always happy," he said. "I've been through this before. I don't get too caught up in every little step. … It can go a lot of different ways. You're just trying to find that range where you're stressing your body and testing it, but not putting it in a position where you're not going to feel good."

After missing the first set of line rushes, Crosby joined linemates Conor Sheary and Patric Hornqvist. He alternated with center Matt Cullen between Sheary and Hornqvist throughout the remaining rushes before changing into a yellow, no-contact jersey for the rest of practice, when his participation was limited.

Tweet from @penguins: Crosby is wearing a yellow no-contact jersey at today���s practice. pic.twitter.com/HZS5QMIgxl

Crosby sat out several drills before alternating with forward Nick Bonino on the first power-play unit with forwards Evgeni Malkin, Phil Kessel and Patric Hornqvist, and defenseman Kris Letang.

"I was just kind of trying to get in there," Crosby said. "I haven't really practiced a lot with our power-play unit. I haven't been for camp and stuff like that, but it was nice to get in there."

Crosby's concussion resulted from him getting tangled up during practice Friday at UPMC Lemieux Sports Complex, he said Tuesday. Following that practice, he said he intended to play in the final preseason game against the Columbus Blue Jackets on Saturday but awoke Saturday with a headache.

Crosby notified trainers and was told he would be held out Saturday.

After joining his teammates for the Penguins Fan Fest event at PPG Paints Arena on Sunday, Crosby did not practice Monday to have concussion testing. It was then determined he had sustained his third concussion in six years.

Crosby was present when the Penguins were given their Stanley Cup championship rings Monday night.

Following practice Tuesday, several Penguins, including Malkin, admitted they were slightly nervous when informed of Crosby's injury, given his concussion history. Crosby missed 101 regular-season games between the 2010-11 and 2011-12 seasons because of concussion-related issues.

Crosby's presence Wednesday helped ease some of his teammates' fears.

"I don't think anyone's celebrating too much, but it's certainly a good sign to see him get out there," defenseman Ian Cole said. "That means it's obviously progressing, which is obviously good news."

Over the ensuing four seasons, Crosby missed no more than 12 games in a season. He played at least 77 games in each of the past three seasons.

Crosby returned to the Penguins on Oct. 4 for his first of two practices before the concussion. He did not play against the Detroit Red Wings on Oct. 5 after captaining Team Canada in the World Cup of Hockey 2016, where he was named tournament MVP with 10 points and three goals in six games.

Because of his World Cup performance and equally impressive outing in the 2016 Stanley Cup Playoffs, Crosby joined Penguins training camp seemingly poised to have a career year. Crosby scored 19 points and six goals in 24 playoff games to win the Conn Smythe Trophy last postseason.

Crosby's season is now put on hold.

"I think you just kind of listen to your body and just see how things go," he said. "I don't think there's a specific timeline each time. It's more of just kind of a constant communication. Just kind of go from there and see how you feel the following day."