There is a rare sense of familiarity about this year's Stanley Cup playoffs.

For just the second time in history, and first since 1945, the final four teams through to the conference finals are the four most recent champions.

The defending champion Los Angeles Kings will play the top-seeded Chicago Blackhawks, who won the Stanley Cup is 2010, when the best-of-seven Western Conference finals opens on Saturday.

The Eastern Conference finals, which also begins Saturday, will be a showdown between the 2011 champion Boston Bruins and the Pittsburgh Penguins, who triumphed in 2009.

The unique lineup has added a sense of mystique to an NHL postseason that is already overflowing with nerve-jangling games and compelling storylines.

Three of the four surviving teams have already been pushed to the brink of defeat. Boston staged a stunning late-game rally before beating the Toronto Leafs in overtime of the decisive seventh game of their first round clash.

The Blackhawks, who finished the lockout-shortened regular season with the league's best record, rallied from a 3-1 series deficit and then were taken to overtime in Game Seven of their second round clash with the Detroit Red Wings.

The Kings at least managed to avoid going into overtime in an elimination game but were still taken to seven games in their second round encounter with the San Jose Sharks.

Only the Penguins, the top seed in the Eastern Conference, have reached the midway mark of the postseason without going the distance, although they have had enough problems along the way.

Pittsburgh captain Sidney Crosby missed part of the season when his jaw was broken by a deflected puck. He has been playing with a special protective face guard but has been cleared to were his normal helmet against the Bruins.

"It actually feels a little bit weird but definitely much better," he said. "In terms of getting air and seeing and everything like that, it's much better."

The Penguins appear to hold the edge in offense with Sidney Crosby and Evgeni Malkin, two of the top four scorers in the postseason this year, on their top two lines but the Bruins defense is among the best in the NHL.

"We've got two lines that we feel are pretty good as well," Boston coach Claude Julien said.

"Maybe we don't have the names that the Penguins have when it comes to the Crosbys and Malkins, but we have guys that have done a great job in the past, that have worked well together and that have given us an opportunity to be a championship team."

The Kings are bidding to become the first repeat champion since the Red Wings in 1997 and 1998 but face a tough task against the Blackhawks.

Chicago won the Presidents' Trophy for having the best record in the regular season and showed their fighting spirit by rallying to beat Detroit in seven games.

"We're excited, we're looking forward to it, we're ready to play," said defenseman Brent Seabrook, who scored the overtime winner against the Red Wings.

"I think we found our game in the later games here in this series, and we're looking forward to getting that one started Saturday night."

The Kings steamrolled their opponents in last year's playoffs but have had work a lot harder this time.

"It's up to the team and players as a whole to rise to the challenge, and we've been able to do that so far," Los Angeles forward Dustin Penner said.

"It's been a lot more wear and tear, I think, on us mentally and physically, but we've been able to overcome it thus far. We're only halfway done."

(Reporting by Julian Linden in New York; Editing by Frank Pingue)