In an ideal world, the final regular-season game between the Rangers and Islanders would have been a prelude to a heated first-round matchup in the Stanley Cup playoffs.

Instead, the two long-running rivals, who have clinched postseason berths, will start next week apart, and perhaps not meet again this year.

The schedule-makers can’t be faulted. Tomorrow’s tete-a-tete at Madison Square Garden is the first time the clubs have met when each has had at least 97 points, according to the Elias Sports Bureau. There may be some skirmishes, and the result still will be significant for playoff positioning, but not as a curtain-raiser for the tournament.

For the Rangers, with 99 points, and the Islanders, with 97 and a game in hand, the final meeting of the regular season could help determine who might finish third in the Metropolitan Division, and who might be the first wild-card team and face the Atlantic Division champion Florida Panthers in the first round. As of now, the Rangers would travel to Pittsburgh, in second place in the Metro, for Games 1 and 2; the Islanders would visit the Panthers.

Nothing is settled, but a loss by the Rangers or two points by the Penguins, who have 102, in Washington on Thursday eliminates the Rangers’ chance for home-ice advantage in the first round. A regulation loss by the Penguins and a regulation or overtime win by the Rangers would keep the home-ice hunt alive. The Rangers host the Red Wings on Saturday; the Islanders host the Sabres on Saturday and the Flyers on Sunday.

The Rangers are 0-2-1 against the Islanders, all with Jaroslav Halak in goal. But with Halak injured, Thomas Greiss is expected to be in net Thursday against Henrik Lundqvist.

Thanks to injuries, both teams are thin on defense, and Dan Girardi’s status was unclear Wednesday.

The Rangers, already missing Ryan McDonagh, did not practice and there was no update on Girardi, who left the ice dazed after being knocked down by Tampa’s Brian Boyle and striking his head on the boards with about a minute left in Tuesday’s game.

“It’s not good, definitely not this time of year,” Lundqvist said. “Definitely hope it’s not too serious, we just have to wait and see. He’s a guy that plays hurt and doesn’t go down unless it’s really painful. Just going to hope for the best.”

If Girardi does not dress, the Rangers still have six healthy defensemen, including rookies Dylan McIlrath and Brady Skjei.

Notes & quotes: McDonagh, who is believed to have suffered a small fracture in his right hand after blocking a shot in Columbus on Monday, remains out indefinitely . . . Veteran defenseman Raphael Diaz, recovering from an injury, practiced in Hartford Wednesday and could be called up as a spare for the first round of the playoffs, when there are no salary limits . . . Tanner Glass did not receive any supplemental discipline for his blindside hit on Tampa’s Vladimir Namestnikov that triggered his ejection Tuesday . . . Three annual team awards will be announced Thursday: the Rangers’ MVP, the Players’ Player Award and the Steven McDonald Extra Effort Award.