Tampa Bay (36-16-3) and Florida (36-14-5) will be the No. 2 and No. 3 seeds from the division, with the higher seed having home-ice advantage for the best-of-7 series.
Florida is 4-2-1 this season against Tampa Bay, the defending Stanley Cup champion. The teams finish the regular season against each other Monday.
"It probably makes [our approach] easier in the sense we know them and they know us," Lightning coach Jon Cooper said. "Oftentimes when you get into playoff series, the Game 1's are kind of that ... like the feel-out game. I say that in a sense because you can only do so much on video, but until you're in the trenches you don't know exactly how the game is going to go and the matchups, etc.
"With playing them so many times, and playing them two times before the playoffs now, it's like there's no secrets. You know the players, and we've played them so many times it's almost -- I don't want to say it's easier, because nothing in the playoffs is ever easy -- but I think guys know what to expect a lot more than if you're not playing a team."
Game 1 has not been scheduled. The playoffs start Saturday.
"We've had some great games with them this year," Panthers coach Joel Quenneville said. "We've had very competitive games, games that are fast. There's some offense, there's some checking, there's a little bit of everything.
"Our games in the regular season kind of built up a different competition between the two teams where we made some inroads as far as trying to close that gap with them. But you only remember the playoff series, which create great rivalries. It's a situation where that familiarity is in place, but rivalries are formed by what happens in the playoffs and this will be a good first step and a real jump in that direction."
Center Brayden Point (four goals, two assists), forward Ondrej Palat (one goal, five assists) and defenseman Victor Hedman (one goal, five assists) each scored six points against the Panthers this season. Center Tyler Johnson scored four goals. Andrei Vasilevskiy was 2-3-0 with a 3.23 goals-against average and .904 save percentage; Curtis McElhinney was 1-1-0 with a 4.58 GAA and .830 save percentage.
Center Aleksander Barkov (one goal, six assists) and Jonathan Huberdeau (three goals, four assists) each scored seven points against the Lightning. Sergei Bobrovsky was 3-2-0 with a 3.23 GAA and .879 save percentage; Chris Driedger was 1-0-1 with a 3.48 GAA and .860 save percentage.
Tampa Bay is led by Point (48 points; 23 goals, 25 assists), Palat (46 points; 15 goals, 31 assists), and Hedman (45 points; nine goals, 36 assists).
Forwards Steven Stamkos and Nikita Kucherov are expected to return for the playoffs. Stamkos, the Lightning captain, has been out since April 8 because of a lower-body injury, and Kucherov has not played this season because of offseason hip surgery.
Vasilevskiy (31-9-1, 2.17 GAA, .926 save percentage in 40 starts) leads the NHL in wins and is tied for third in shutouts (five). McElhinney was 4-6-2 with a 3.09 GAA, .875 save percentage and one shutout in 12 games.
Huberdeau leads the Panthers with 61 points (20 goals, 41 assists) in 54 games, Barkov has scored 57 points (26 goals, 31 assists), and center Carter Verhaeghe has scored 35 points (17 goals, 18 assists) in 42 games. They are among the eight Panthers skaters with at least 10 goals.
Bobrovsky is 19-8-2 with a 2.91 GAA and .906 save percentage in 31 games (30 starts); Driedger is 13-6-3 with a 2.17 GAA, .923 save percentage and two shutouts in 22 starts; rookie Spencer Knight is 4-0-0 with a 2.32 GAA and .919 save percentage in four games (three starts).
The teams have never played each other in the playoffs.
"For instance, [the Columbus Blue Jackets], where we hadn't played them very often and then we played them in the playoffs," Cooper said. "Last year we only played them once in the regular season before playing them in the playoffs (a five-game win in the Eastern Conference First Round).
"Florida, I feel like it's been a ton of games, so that 'familiarity breeds contempt' line really fits, but we know what to expect."
Tampa Bay, which qualified for a fourth straight season, defeated the Blue Jackets, Boston Bruins, New York Islanders and Dallas Stars to win the Cup last season.
Florida lost to New York in four games in the best-of-5 Stanley Cup Qualifiers.
"We've been playing the right way almost the whole season," Barkov said. "Most of the season we play the right way. We're coming up with the wins and obviously we know Tampa [Bay] really well. We've played against them a lot this year and even last year and we're going to play against them a lot this year moving forward. We know them pretty well and they know us pretty well. It's going to be a battle between us two."
The series winner will play the winner of the series between the Carolina Hurricanes and Nashville Predators in the second round.
NHL.com independent correspondents Corey Long and Alain Poupart contributed to this report