The Western Conference series starts Wednesday. The Eastern Conference series begins Thursday.
[RELATED: Second Round schedule]
1. Sidney Crosby vs. Alex Ovechkin, Round 3
And so they meet again, Penguins captain Sidney Crosby and Capitals captain Alex Ovechkin headline the marquee matchup of the second round. Game 1 is at Verizon Center in Washington on Thursday (7:30 p.m. ET; NBCSN, SN, TVA Sports 2).
It's the third time the Penguins and Capitals have played in the postseason with Crosby and Ovechkin taking center stage. The good news for Crosby and the Penguins is they won the previous two series each time en route to winning the Stanley Cup in 2009 and 2016.
Ovechkin hardly is to blame for the Capitals' struggles against Pittsburgh. He has 21 points (10 goals, 11 assists) in 13 playoff games against the Penguins, including seven points (two goals, five assists) in six games last season.
The Penguins have been the better team each time, as evidenced by them winning the series last year despite Crosby being held to two assists. He had 13 points (eight goals, five assists) in the seven-game series in 2009.
Video: WSH@TOR, Gm4: Ovechkin cranks slapper for PPG
2. Breakout stars
Oilers center Connor McDavid had four points (two goals, two assists) in six games against the San Jose Sharks in the first round, but that's minimal production for the Art Ross Trophy winner, who had 100 points (30 goals, 70 assists) during the regular season.
Blues forward Vladimir Tarasenko similarly could be lying in the weeds after he had one goal on 21 shots in five games against the Minnesota Wild. He scored 39 goals during the regular season.
Ducks center Ryan Kesler had one assist in the four-game series sweep against the Calgary Flames. Predators forward James Neal had the same stat line in a four-game series sweep against the Chicago Blackhawks.
Kesler had 58 points (22 goals, 36 assists) in 82 regular-season games. Neal had 41 points (23 goals, 18 assists) in 70 games.
And Rangers left wing Chris Kreider had one assist in a six-game series win against the Montreal Canadiens. He scored 28 goals during the regular season.
Video: STL@MIN, Gm5: Tarasenko tallies after crafty footwork
3. Connor McDavid mania
McDavid has had all eyes on Edmonton since the Oilers won the 2015 NHL Draft Lottery two years ago. He has the Oilers in the playoffs for the first time since 2006 and now the focus on him and his team sharpens with half the teams eliminated.
McDavid and the Oilers defeated the defending Western Conference champions in the first round and now face another experienced team in the Ducks, who have played 47 postseason games since 2013. The Sharks had played 41 since 2013 before facing the Oilers.
McDavid will be playing against two of the most physical, experienced centers in the League in Kesler and Ryan Getzlaf. Look for Kesler to get the McDavid matchup as often as the Ducks can get it. He's a finalist for the Selke Trophy this season.
Game 1 is at Honda Center in Anaheim on Wednesday (10:30 p.m. ET; NBCSN, SN, TVA Sports).
4. Predators push for history
Half the teams remaining have not won the Stanley Cup (Washington, Ottawa, St. Louis, Nashville), but the Predators are the only team that has never advanced past the second round in their history.
The Predators are in the second round for the second straight year and the fourth time in their history. They lost in seven games to the Sharks in the second round last season. They also lost in the second round in 2011 and 2012.
Game 1 between the Predators and Blues is at Scottrade Center in St. Louis on Wednesday (8 p.m. ET; NBCSN, CBC, TVA Sports).
Video: CHI@NSH, Gm4: Sissons' wrister banks in off Crawford
5. Erik Karlsson's health and ice time
It's not a stretch to say Senators captain Erik Karlsson is the best defenseman remaining in the playoffs. He's a two-time Norris Trophy winner (2012, 2015) and a finalist again this season.
However, Karlsson told ESPN.com on Sunday that he has been playing with two hairline fractures in his left heel and received injections to play in the first round against the Boston Bruins. He had six assists and averaged an NHL-high 30:23 of ice time per game.
It's also not a stretch to say the Senators' chances of defeating the Rangers largely hinge on Karlsson's ability to be the dominant, game-changing player he is known to be. His health and ice time will be in focus, especially early in the series.
Game 1 is at Canadian Tire Centre in Ottawa on Thursday (7 p.m. ET; CNBC, CBC, TVA Sports).
6. Penguins getting healthy, but will they be rusty?
The Penguins will have six full days off before playing Game 1. That can be good and bad.
The good: The Penguins have had time to heal some wounds and get some players back on the ice. Forward Chris Kunitz (lower body) and defenseman Chad Ruhwedel (upper body) have been cleared for contact and could play Thursday. Forward Carl Hagelin (lower body) is skating and there's hope he can play during the second round.
Kunitz, Ruhwedel and Hagelin did not play in the first round. Goaltender Matt Murray (lower body) has not resumed skating.
The bad: The Penguins might have to shake some early rust because of how long they've been off. The Capitals, meanwhile, finished the Toronto Maple Leafs in Game 6 on Sunday. They took Monday off and will practice Tuesday and Wednesday. There should be no rust.
Video: PIT@CBJ, Gm4: Guentzel roofs rebound for late SHG
7. Senators-Rangers center swap back in focus
Senators center Derick Brassard and Rangers center Mika Zibanejad will forever be linked because they were traded for each other July 18. Now they play against each other and their former teams for the right to go to the Eastern Conference Final.
Brassard led the Senators with eight points (two goals, six assists) in the first round. In the previous three-plus seasons with the Rangers, he helped them reach the Stanley Cup Final in 2014 and the Eastern Conference Final in 2015.
Zibanejad, who played his first four NHL seasons with the Senators, the team that selected him with the No. 6 pick in the 2011 NHL Draft, led the Rangers with four points (one goal, three assists) against the Canadiens.
Video: OTT@BOS, Gm3: Brassard slams home Ryan's nice dish
8. A matchup of the League's hottest goalies
No starting goalie in the first round allowed fewer goals than Pekka Rinne of the Predators, who gave up three on 126 shots in four games. Second on the list was Jake Allen of the Blues, who allowed eight on 182 shots in five games against the Wild.
Rinne had a 0.70 goals-against average and .976 save percentage in the first round. Allen had a 1.47 GAA and .956 save percentage.
Allen has been the hottest goalie in the League since Feb. 1, when Martin Brodeur took over as his goalie coach and Mike Yeo replaced Ken Hitchcock as Blues coach. Including the regular season, Allen is 20-8-2 with a .942 save percentage and 1.78 GAA in 30 games since Feb. 1.
Not to be outdone, Rinne is 9-3-1 with a .954 save percentage and 1.28 GAA in 13 games since March 16.
Video: CHI@NSH, Gm4: Rinne turns away Panarin's long wrister
9. Ryan's resurgence
Senators general manager Pierre Dorion said April 10, the day after Bobby Ryan ended a 13-game goal drought that dated to Feb. 16, that he thought the forward was playing well despite not scoring a lot and would be a productive player during the playoffs.
Spot on, so far.
Ryan scored four goals in the first round. He had two goals in 21 games after the All-Star break.
The production the Senators got from Ryan and Brassard, neither of whom had consistently productive regular seasons, was huge in getting past the Bruins, who averaged the most goals per game in the League after Feb. 1 (3.41).
10. Fowler's pending return
Ducks defenseman Cam Fowler returned to practice Sunday after missing the first round because of a knee injury he sustained April 4. Fowler, who led the Ducks with an average ice time of 24:50 per game, could be in the lineup for Game 1.
His return would be a huge boost to the Ducks, who no doubt have more to worry about against McDavid and the Oilers than they did against the Calgary Flames in the first round.
The Oilers scored 2.00 goals per game and their power play was 12.5 percent against the Sharks. They averaged 2.96 goals per game in the regular season and their power play was fifth in the League at 22.9 percent.