NHL

Backup goalie Biron plays well, but Rangers blanked by Blues

The grand plan to get Martin Biron 15-to-18 starts so Henrik Lundqvist is as fresh as possible down the final stretch into the playoffs is wholly dependent on the backup netminder’s ability to play well enough in order to earn the trust of Rangers coach John Tortorella.

Or have you forgotten last year’s original plot to get Steve Valiquette double-digit starts?

Taken from that perspective, Biron’s outstanding performance is the most significant Big Picture item to emerge from the Blueshirts’ 2-0 defeat to Ty Conklin and St. Louis last night at the Garden, in what was the Blues’ first shutout of the Rangers in the 129-game all-time series between the clubs.

PHOTOS: RANGERS LOSE TO BLUES, 2-0

Biron — blameless on the screened 3-on-2 goal that Alex Steen wired top shelf 5:16 into the second that stood alone until Steen’s empty-netter with 3.9 seconds to go — was sharp throughout in a critical bounce-back performance following his Oct. 21 home clunker against Atlanta in which he surrendered five goals on the first 22 shots he faced.

“I have to go in there and win games,” said Biron, tested early and regularly throughout a scoreless first period. “That’s how demanding I am of myself and how demanding this job is.”

The most a goaltender can do is give his team its best chance to win. And that is exactly what Biron did.

“He certainly gave us the opportunity,” said Tortorella, who can breathe easier regarding his rotation. “I was happy with his game.”

There wasn’t much else to be happy with. The Rangers tried, but were a step behind, unable to pierce the trap. They tried, but the other guys, who have won seven straight and are 9-1-2, tried either harder or smarter, or both.

The Rangers not only didn’t win enough battles, they couldn’t even win their fair share of them on a five-minute power play that ran midway through the third.

“I thought we were outworked on the walls and didn’t win the battles we needed to,” Ryan Callahan said. “Their penalty kill is very aggressive. We didn’t match their effort there and allowed our PP to be outworked by their PK.”

The Rangers, who failed on a five-minute power-play Friday against the Devils, had two chances on this one, but after Conklin stopped Callahan in front, Artem Anisimov flubbed an open net on the rebound at the left doorstep.

Alex Frolov actually did slip one past Conklin with 1:56 to go in the first period, but the “goal” was waved off by the habitually incompetent Bill McCreary. The referee incorrectly ruled the puck had been played with a high stick in the neutral zone by St. Louis defenseman Nikita Nikitin and blew his whistle when Conklin got his stick on the puck a moment before Frolov.

“I knew the whistle had blown,” said Conklin, who backs up Jaroslav Halak. “I didn’t know why.”

Tortorella scratched Todd White despite the veteran’s strong work in Friday’s victory over the Devils in order to get Evgeny Grachev into the lineup. It is believed Grachev, who did not get off the bench in the third until the 19:56 mark and who got 4:10 overall, was being showcased, but it wasn’t much of a show.

It wasn’t much of a show and it wasn’t much of a showing by anyone other than Biron, but in the grand scheme of things, his work was much better than nothing.

larry.brooks@nypost.com