Jonathan Quick’s 800th career start quickly turned into a disaster.

For the second time in three games, the Rangers backup goaltender — forced into the starting role with Igor Shesterkin on injured reserve — was pulled, this time with 7:37 left in the second period Wednesday after allowing six goals during the 8-4 loss against the Senators.

He managed just 11 saves (a .647 save percentage) and dropped to 0-4-0 since taking over as the starter.

Spencer Martin took over for the nearly 40-year-old goaltender and was cheered by fed-up fans inside the Garden after covering up the puck.

For some tallies, there wasn’t much Quick could do.

The Blueshirts defense was porous. One goal bounced off Braden Schneider’s skate and into the net.

Quick, though, had struggled the previous three games, too, entering Wednesday with an .814 save percentage and 16 goals allowed across that stretch. He was also pulled during Saturday’s 10-2 loss at Boston.

“It’s not an easy one to evaluate, I think, under the circumstances,” head coach Mike Sullivan said when asked about Quick’s performance, before shifting into praise of his goaltender. “Here’s what I’ll tell you about Quickie: he’s a fierce competitor, and he gives you everything he has. Every day that he steps on the ice. I just have so much admiration and respect for what he brings to the table.”

With Shesterkin on injured reserve, Quick will need to remain the Rangers starter for the foreseeable future.

The Blueshirts all expressed belief and optimism in Quick — the winningest American-born goalie in NHL history — after Shesterkin sustained a noncontact, lower-body injury Jan. 5.

But by the time he veered over to the bench and Martin replaced him Wednesday, Quick’s stint as starter had already started to mirror the Rangers season and spiral out of control.

Gabe Perreault recorded the first multi-goal game of his career, including one where the 20-year-old forward jumped into a 2-on-1 with Mika Zibanejad, took a pass and deposited the puck past Leevi Meriläinen.

“A little bit,” Perreault said, when asked if it showcased what he can do with the puck. “I mean, obviously it’s nice to get one, but at the end of the day, we lost, so it doesn’t really matter.”

From demotion out of the top six to the first line — for at least the beginning of the game.

Alexis Lafrenière’s roller coaster of a season in a roller coaster of a Rangers career took another turn Wednesday.

Sullivan bumped Lafrenière to the top group just two days after the struggling winger was sent to the third line in a performance-based move.

By the time the first period reached its midway point, though, Sullivan had already blended together the lines again, with Lafrenière on a line with Artemi Panarin and Vincent Trocheck.

Zibanejad and J.T. Miller skated on a line with Perreault. Noah Laba centered Will Cuylle and Brennan Othmann.

Matt Rempe was out of the lineup for a second consecutive game while the Rangers attempted to allow his thumb to recover.