The first week of the NHL postseason has been about as unpredictable as anyone could imagine, even in a sport where upsets are the norm, home-ice advantage is often meaningless and a hot goaltender can overshadow everything else that's happening.

Perennial Stanley Cup favorite Chicago is down 0-3 to Nashville and the NHL-leading Washington Capitals trail Toronto 2-1 in their first-round series, but that's only part of the story. Seven of the first 24 games have featured a blown lead of two goals or more, 11 have gone to overtime and winning goals have come from some of the unlikeliest of sources.

Just Monday, all four games went to OT for only the third time in NHL history and first time since 1985, including the Blackhawks and Capitals blowing two-goal leads to sow more seeds of doubt and give the Predators and Maple Leafs a jolt of confidence.

"Our guys think they're a good hockey team, and they're playing a good hockey team," Toronto coach Mike Babcock said. "But I think you gain respect for yourself in the process and you start believing that maybe you can do this."

The Blackhawks' core has three Stanley Cups in the past seven years and a lot experience to lean on. Washington only has playoff disappointments in the rearview mirror, and panic is starting to set in about another early exit with a crucial Game 4 looming Wednesday night (7 p.m. ET, NBCSN).

Alex Ovechkin and the Capitals were heavy favorites to beat the young Maple Leafs, but it hasn't looked like it as all three games so far have gone to overtime.

"It's a lot closer match than people let on," coach Barry Trotz said after losing Game 3 in Toronto. "It's not David and Goliath."

Chicago versus Nashville looked like it, but the Blackhawks face a daunting task trying to become just the fifth team in NHL history to overcome a 3-0 series deficit. They have some company there with the Minnesota Wild down 3-0 to the St. Louis Blues (9:30 p.m. ET, NBCSN) and the Calgary Flames down 3-0 to the Anaheim Ducks (10 p.m. ET, USA).

Trotz has tried to argue that the talent gap isn't big between even the top and bottom playoff teams, but there's a chance for four sweeps. There were only four sweeps combined in the first round of the past seven playoffs.

Perhaps the defending Cup champion Pittsburgh Penguins going up 3-0 on the Blue Jackets isn't the biggest shocker given how Columbus stumbled down the stretch, but goaltender Sergei Bobrovsky's disastrous performance is stunning. The favorite to win the Vezina Trophy opened the playoffs 0-3 with a 3.49 goals-against average and league-worst .897 save percentage after finishing first in the regular season (2.06 GAA, .931 save percentage).

Some of the biggest goals so far have come from surprising players, too, from Zack Kassian scoring two game-winning goals for the Edmonton Oilers to put them up 2-1 the San Jose Sharks to Tanner Glass having a game-winner for the New York Rangers. Even the Ottawa Senators have gotten goals from defenseman Dion Phaneuf and struggling winger Bobby Ryan to go up 2-1 on the Boston Bruins heading into Game 4 Wednesday (7:30 p.m. ET, USA).

"I always say that you make your money during the season, but you make your reputation in the playoffs, and right now he's showing everybody that he's a gamer," Senators coach Guy Boucher said of Ryan.


AP Sports Writer Kyle Hightower in Boston and The Canadian Press contributed.


More AP NHL hockey at https://apnews.com/tag/NHLhockey


Follow Hockey Writer Stephen Whyno on Twitter at http://www.twitter.com/SWhyno .