Sidney Crosby doesn't scare easily. But the future of the Pittsburgh Penguins had him unnerved.

Center Evgeni Malkin and defenseman Kris Letang, Crosby's teammates on all three of his Stanley Cup victories, were at the end of their contracts last season. Free agency loomed. Rare was the team, in hockey or any other sport, that would keep an aging core together that hadn't advanced past the playoffs' opening round in four straight seasons — let alone find a way to do so under a flat salary cap.

"I was sweatin'," Crosby told ESPN. "You know how it works. The longer it goes, the closer it gets to free agency, the greater the chances are you might want to test it. You're trying to balance being optimistic with being realistic about the fact it was a possible [they'd leave]."

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Penguins coach Mike Sullivan led all three players to Stanley Cup wins in 2016 and 2017. He couldn't begin to imagine how Crosby would captain a Pittsburgh team without Malkin and Letang on the roster.

"It would have been hard for him. Those three have been through a lot together," Sullivan said. "They've had their fair amount of successes, but they've also had their disappointments. I think it means a lot to him to continue to try to win; but in particular, to continue to try to win with those guys.

"I can't imagine what it would have been like for Sid to go through. I'm glad we don't have to find out."

Letang, 35, signed a six-year contract extension on July 7 worth $36 million. Five days later, Malkin, 36, signed a four-year, $24.4 million contract. That was right after news leaked that Malkin intended to test free agency, when tense talks with Pittsburgh finally stalled.

Sullivan remembers being optimistic that they'd both return to Pittsburgh — until hearing about Malkin's negotiations, that is.

"I always believed we'd get it done, up until maybe the last 48 hours before free agency with Geno," he said. "That was the only time that doubt crept into my mind. But in my heart I believed that we'd be able to retain these guys. I know what it means to them."

What did it mean to Crosby?