Paul Blackburn set for return to ‘comfort zone’ as Kodai Senga officially hits injured list

The severity of Kodai Senga’s right hamstring injury was still unclear to Mets officials late Friday afternoon, but the team had already moved ahead in filling his rotation spot.

Paul Blackburn, the team’s de facto sixth starter, will shift from the bullpen to start Wednesday in Atlanta, according to manager Carlos Mendoza.

Senga’s absence will mark the first missed start by one of the five starters who began the season in the Mets’ rotation.

Senga strained his right hamstring Thursday covering first base and a day later was placed on the injured list, with reliever Max Kranick recalled from Triple-A Syracuse.

Senga was set for a late afternoon MRI exam before the Mets’ series opener against the Rays at Citi Field.

Blackburn, who had last pitched Sunday in Colorado — where he recorded a four-inning save — was available from the bullpen for the series opener.

Mendoza said Blackburn, if he wasn’t used Friday, could potentially be available in relief Saturday, but not beyond that as he rests for his scheduled start.

Blackburn said it “sucks” to have lost Senga, given the manner in which the right-hander was pitching — he leads MLB with a 1.47 ERA in 13 starts — but Blackburn appreciates the opportunity to rejoin the rotation.

“That is kind of where my comfort zone lies,” Blackburn told The Post. “It is what I have done my whole career. I have my whole routine set for that.”

Blackburn returned from the injured list to start against the Dodgers on June 2, when he pitched five scoreless innings as part of a six-man rotation.

Blackburn was placed in the bullpen after that outing.

“Every team will go through [injuries], but I feel we are equipped to handle it,” manager Carlos Mendoza said. “We have already got a guy like [Blackburn] on the active roster and we have got more guys that are close to joining the team.”

On the forefront is Frankie Montas, who allowed eight earned runs over 1 2/3 innings for Triple-A Syracuse on Friday in a minor league rehab start.

Montas, according to president of baseball operations David Stearns, will need an additional appearance in the minors before a decision is reached on activating him.

Montas, who is rehabbing a high-grade lat strain, has pitched poorly in all three of his starts for Syracuse.

“I think he is still feeling his way back,” Stearns said. “This was a pretty significant lat injury. He did a good job working through his progression and I think he is still searching a little bit. Physically, we are trending in the right direction and now it’s just getting him back into the rhythm. This is very similar to a spring training ramp up where you try not to focus on results too much early and then as you get a little bit later in the ramp up you want to start seeing outs. That is where Frankie is right now.”

Sean Manaea is further behind.

The left-hander’s initial rehab appearance from an oblique strain was earlier in the week for Single-A Brooklyn.

Stearns downplayed the idea the Mets may soon have too many rotation options.

Clay Holmes, David Peterson and Griffin Canning have all excelled and Tylor Megill has pitched well enough to remain in the rotation.

“It’s very rare where you actually get to the point where you have too many starting pitchers that you can roster,” Stearns said. “If somehow, at some point, we get to that this season I will have to make some decisions and I imagine those would be difficult decisions, but for now I am very happy with how this group that we’ve had to this point has pitched. I am excited we continue to get healthier and get guys like Frankie and then ultimately Sean back in the rotation. I think that will make us stronger. Certainly deeper.”