It was the great American poet Eminem who wrote, “You only get one shot, do not miss your chance to blow / This opportunity comes once in a lifetime.” Words ingrained into the minds of a generation.

And here’s the question I’ve always asked myself: How do you know when it’s that one shot? How are you supposed to know when that opportunity has arrived?

So often, we only realize that critical juncture in hindsight.

In the wake of Zlatan Ibrahimovic's spectacular, social-media shaking debut, it feels like a defining moment is coming this week for Toronto FC, the New York Red Bulls. Both MLS teams open their 2018 Concacaf Champions League semifinal this week. Both teams have a chance to cement their place in North American soccer history.

Toronto FC have already penciled themselves into the record books: The 2017 Canadian and MLS Cup champions set league records, winning a treble and laying a multi-layered claim to the best single season in MLS history. Hopefully they feel we all recognize that and have given them their due. Unfortunately, though, those “best team” candidates are generally written in erasable notations. In a few years, a new team will come along to capture our subjective minds as a new group dominates the conversation.

There’s one true to affirm your legacy in MLS right now, to be invincible in MLS perpetuity. Take down the last white whale in North American soccer:

Win CCL.

Claiming the confederation crown wouldn't just mark an accomplishment for a single club, but a victory for the league. It’s a statement of achievement that recognizes the journey to get there. Claiming the CCL crown pulls together fans of both countries. It’s stepping onto the moon and planting the flag. And only one club gets to be first.

Toronto’s 2017 season will always be the one with the treble. A Red Bulls semifinal run will be remembered fondly by their fans for the Tijuana blowout if nothing else. But the CCL crown, that's the once-in-a-lifetime opportunity. These teams and players that look capable of winning the whole thing: Do they appreciate it? Should they? Does it raise performance to understand you have the weight of history on the line?

Both Toronto and the Red Bulls deserve credit for getting this far. But there’s a big difference between credit and immortality. Two legs, one shot. Don't miss your chance to blow.