"I never really had a doubt, to be honest," MacKinnon said. "He's so tough."
That being said, Crosby said it was not an easy road to get here the past week.
"It's a long process," he said. "I met with a couple different doctors, and obviously we were playing a couple games before the break. I was ruled out for those. And then a couple days here later, I've talked to docs here and had some good dialogue with the coaches and just seeing where I was at.
"Obviously today was the first time I skated with the group. I was skating on my own prior to that. Everything went well. I feel good from that standpoint."
And when Crosby feels good, especially while wearing a Canadian jersey, the results usually are too.
He has won gold medals with Canada at the 2005 IIHF World Junior Championship, the 2010 Vancouver Olympics, when he scored the golden goal in overtime against the United States, the 2014 Sochi Olympics and the 2015 IIHF World Hockey Championship, and also captained his country to the title at the World Cup of Hockey in 2016.
In the process, Canada has won 25 straight games in tournament play with Crosby in the lineup, having not lost since a 5-3 loss to the United States in the preliminary rounds of the Vancouver Games on Feb. 21, 2010.
"This is an awesome opportunity, something I haven't done in a long time," Crosby said. "I wanted to be part of this group and obviously also wanted to make sure that I can play at the level that you need to to compete here.
"Everybody seemed comfortable with that, and I feel good about it."
So, too, does MacKinnon, especially since he'll be playing on the same line with Crosby. The two scrimmage against each other in the Halifax area during the summer but normally line up on opposite sides. Stone will be the third member of that line.
"Obviously it's incredible," MacKinnon said of playing with Crosby. "He's one of the best players ever.
"Being close to him, it's not too weird for me. It's easy communication. We spend so much time together. If I didn't know him, I'd probably be really, really intimidated. Wouldn't know what to say to him.
"He's one of the smartest players ever to play."
You don't have to sell Mike Sullivan on that. He already knows.
Sullivan is the coach of the Penguins and was behind the bench when Crosby and his teammates won the Stanley Cup in 2016 and 2017. For the next two weeks, however, they'll be on opposite sides with Sullivan coaching the United States.
"It's going to be a little awkward for me not having him on the same bench," Sullivan admitted.
Speaking of awkward, that's exactly how Canada's Seth Jarvis felt when he walked into the dressing room and found out his cubicle was directly next to Crosby's.
"Surreal," the 23-year-old Carolina Hurricanes forward said. "I mean, when he scored the golden goal that won Canada the gold medal against the U.S. at the 2010 Vancouver Olympics, I was 8 years old attending a friend's birthday party in Winnipeg.
"Now I'm sitting next to him and playing on the same team. Unbelievable. Just so happy to see him out there."
He's not the only one.