By Steve Keating

(Reuters) - Pittsburgh's Sidney Crosby and Washington's Alex Ovechkin will return to the National Hockey League (NHL) playoff stage this week eager to steal the spotlight and steer their respective teams to a Stanley Cup.

While the start of the playoffs on Wednesday marks the most exciting time of year for hockey fans, it also comes with dark clouds on the horizon with a labor agreement set to expire in September and signs of a bitter dispute looming large.

But for two months it is the battle for hockey's holy grail that NHL fans will be focused on as eight teams from each of the Eastern Conference and Western Conference try to navigate their way through four punishing best-of-seven series before one finally hoists the silver Cup.

No team knows more about the playoff grind than the Detroit Red Wings, who return to the playoffs for the 21st consecutive year, while the Florida Panthers are joining the party for the first time since 2000.

Canadian attention will be fixed on the Vancouver Canucks and Ottawa Senators, who carry the hopes of a hockey-mad nation that has not produced a champion since the Montreal Canadiens won the last of their 24 Stanley Cups in 1993.

The playoffs are rich with intriguing story lines but none more tantalizing than a possibility of Crosby and Ovechkin - two of the NHL's biggest names - rekindling the highlight-reel performances they produced in the 2009 postseason.

The rivalry, widely considered as one for the ages, reached a crescendo when both players engaged in a breathtaking display of one-upmanship for much of the Eastern Conference semi-final, most notably in Game Two when each had a hat-trick.

With Crosby out for most of the last 15 months recovering from concussion-like symptoms and Ovechkin slipping in and out of a scoring slump, the duo fell off the radar but could be set to return to the spotlight as the Cup chase begins.

While the prospect of an Ovechkin-Crosby showdown presents a mouth-watering possibility, each team has more pressing concerns with Pittsburgh playing the state-rival Philadelphia Flyers and Washington up against the reigning Stanley Cup champion Boston Bruins in the first round.

All eyes will be on Crosby to see how the Pittsburgh captain handles the post-season pounding, but all signs point to the Canadian being close to his top form after recording eight goals and 37 points in 22 games.

In Crosby's absence, team mate Evgeni Malkin stepped up to claim the Art Ross Trophy as the NHL's scoring champion for the second time in four years and is a leading candidate for the Hart Trophy, given to the NHL's most valuable player (MVP).

The Capitals will be relying heavily on Ovechkin, who is coming off a career-low 65-point season, to return to the form that made him a two-time league MVP and one of the game's most feared snipers.

Goaltending can carry a team in the playoffs and the East's top seed New York Rangers, who will meet the Senators in the first round, have one of the best in Swede Henrik Lundqvist, who finished in top five in all of the key goaltending categories.

No team will have more experience in net than the New Jersey Devils where Martin Brodeur, the NHL's all-time leader in wins and shutouts, will be manning the crease when the Devils open against the Panthers.

The big, bad Bruins will need another playoff MVP effort from netminder Tim Thomas if they are to become the first team to repeat as champions since the Red Wings accomplished the feat in 1997-98.

In the West, Vancouver Canucks netminder Roberto Luongo appears ready to rumble after earning a shutout in his team's final regular season game to clinch the Presidents' Trophy as the NHL's top team for the second straight year.

The top-seeded Canucks, who will face the Los Angeles Kings in the first round, have the look of a team on a mission after letting the franchise's first Stanley Cup slip through their fingers with a Game Seven home loss to the Bruins last year.

The St. Louis Blues, who launch their Cup bid against the San Jose Sharks, started the campaign as one of the NHL's worst teams and finished as one of the best after an early coaching change installed Ken Hitchcock behind the bench.

While Hitchcock's impact was undeniable, it was the work of goalies Brian Elliott and Jaroslav Halak that allowed the Blues to challenge for top spot in the West as the duo allowed the fewest goals (165) and recorded a league-best 15 shutouts.

Other first round matchups will have the Red Wings taking on the Nashville Predators and the league owned Phoenix Coyotes against the Chicago Blackhawks.

(Reporting by Steve Keating in Toronto; Editing by Frank Pingue)