Acquiring Blake Coleman and Barclay Goodrow at the 2020 NHL trade deadline helped the Tampa Bay Lightning win the Stanley Cup. No such moves will be possible in their attempt to repeat.

“We have zero dollars of cap space to acquire a player between now and the trade deadline,” general manager Julien BriseBois said. “Literally zero dollars. That’s the obstacle.”

That obstacle isn't unique to the defending champions going into a trade deadline like none other in league history. Eighteen of 31 teams have $1 million or less of salary cap space and the cap ceiling won't go up a penny next season, so things are tighter than ever.

Prominent players like Buffalo's Taylor Hall and goaltenders Jonathan Bernier and Devan Dubnyk seem likely to move, but even hockey's most seasoned executives aren't sure what to expect before the clock strikes 3 p.m. Eastern on April 12.

"There’s so much unknown because of the cap," New York Islanders GM Lou Lamoriello said. “The cap is going to be flat next year. So any contract that you take on that is more than one year is going to disrupt whatever you’re doing next year and will put you in worse shape. So that complicates the matter without the cap increases, but it’s the same for everyone."

The seven Canadian teams are in a “tougher spot," Toronto GM Kyle Dubas acknowledged, because of a weeklong mandatory quarantine for any player acquired from the U.S. That's half the quarantine imposed earlier this season but still makes it more difficult to swallow paying a hefty price for a player who might be available for only 10 regular-season games before the playoffs begin.

And that's if teams can agree to a trade with so little cap room. Tampa Bay, Washington, Vegas and Montreal don't have the space to add even a player making the league minimum, according to PuckPedia calculations, and several others would need to clear room to add anyone with even a modest salary.

“A lot of teams are in the same situation we’re in where they literally have no cap space or very, very little — not enough to add a player without subtracting,” BriseBois said. “The teams that are kind of on the bubble, I don’t know how what’s ultimately going to guide their decisions. Are they going to try to add? Are they going to sell? Will there be more teams just standing pat? I don’t know, but it’s going to be interesting to find out.”

Philadelphia and Columbus are among those on the playoff bubble with tradeable assets. The flailing Flyers have lost three of five since GM Chuck Fletcher said they're “not looking at selling right now." That can obviously change.

The buyers are easier to identify: Lamoriello's Islanders lost captain Anders Lee to a season-ending right knee injury, Dubas' Maple Leafs look like the class of the North Division with perhaps a hole or two to fill and Edmonton might be a top-four defenceman away from challenging Toronto.

“If you’re talking about trying to go out and get a legit top-four — any, a lefty or a righty — defenceman, No. 1 there’s not a lot of them that are going to be available,” Oilers GM Ken Holland said. “And those that are going to be available, the price is going to be high.”

A couple of top defencemen could also stay put if Nashville remains in playoff contention and keeps Ryan Ellis and Mattias Ekholm. Right-shooting Blue Jackets defenceman David Savard is a pending free agent and arguably the most sought-after player on the market.

Hall and New Jersey's Kyle Palmieri fit the Islanders' need without Lee, though they aren't the only team looking for that kind of player.

“We’re always trying to find a scoring winger,” Lamoriello said. "Everybody is. That’s not something that’s easy to do."

It's also not easy to find a reliable goaltender, which Colorado and Washington would love to add as playoff insurance in win-now mode. Maybe that's Bernier or Carolina's James Reimer, who are currently injured, or a bigger swing at someone like Jonathan Quick of Los Angeles.

Players like Quick or Anaheim forward Rickard Rakell would normally be important additions this time of year because they're signed beyond this season. That was Tampa Bay's thinking getting Coleman and Goodrow for at least two playoff runs, but the salary cap remaining flat at $81.5 million changes the equation.

“Usually you’d put a premium on getting a player that has future years,” Dubas said. “It’s a little bit more complex this year knowing that very likely it’s going to be at 81.5 again, the cap, so anything that we take from next year’s allotment, it impacts a number of different things as you can well imagine. It’s a rare time where probably a rental is a better fit."

Even acquiring a pending free agent isn't simple for the league's top contenders. Washington's Brian MacLellan would have to trade from his roster to get a veteran goalie or upgrade elsewhere, and colleagues who are in sellers can make the Capitals or another team pay for unloading salary.

“There’s teams who do have cap space that are willing to take on space, so if you want to buy cap space, that’s available,” said Montreal GM Marc Bergevin, who needed the Sabres to retain half of Eric Staal's salary to get him in a trade for two draft picks. “But there’s a price to pay for that, and depending on the amount you’re trying to buy, then the price becomes steeper.”

All of that adds up to an uncertain trade deadline where no one's quite sure how much movement there will be.

"Your guess is as good as mine," BriseBois said.

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Follow AP Hockey Writer Stephen Whyno on Twitter at https://twitter.com/SWhyno.

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