BOSTON -- Zack Greinke pitching a must-win postseason game was among the surest of sure bets during the six-time All-Star’s peak. It’s explicitly why the Astros acquired him ahead of the 2019 Trade Deadline.

Now, with a 2-1 deficit in the American League Championship Series and potential elimination inching closer, Houston will turn to its up-and-down veteran for Game 4 at Fenway Park on Tuesday, Astros manager Dusty Baker announced following the club’s 12-3 loss in Game 3 on Monday.

And Greinke will do so in territory that has as much urgency as uncertainty.

Baker said when this series began that Greinke was stretched out to roughly 40 pitches. Asked if that length was accurate, and how many innings he might be able to offer, Greinke said: “We'll see. I haven't gone real deep recently, but we'll just see what happens and we'll be ready and we'll go from there.”

How long is Baker’s leash, especially given that Houston’s starters have accounted for just 5 1/3 of the 26 innings pitched in this series, mostly because they’ve been tagged early and given up a combined 14 runs?

“As long as he can go,” Baker said. “As long as his endurance is fine. Like I said, as long as he can go.”

Greinke’s lone outing this postseason was a scoreless fourth inning in Game 3 of the AL Division Series in Chicago, when he relieved Yimi García mid-inning after García surrendered four runs. And Greinke hasn’t started a game since a four-inning outing on Sept. 19 against the D-backs, so most signs point to an abbreviated outing.

“It's a tough team we're facing,” Greinke said. “They’re swinging good, and I mean, I’ll just try to make pitches. My whole career has been based around trying to make pitches, and that's all you can do, and they’ve got a pretty tough lineup over there. The better pitches you make, the better chances you have. The more mistakes you make, the worse your success will probably be.”

Greinke missed time in September due to a positive COVID-19 test, and he then suffered neck soreness that necessitated a stint on the injured list. Both of those issues hindered his ability to build back his arm strength by the end of the regular season.

Thus, Greinke was moved to the bullpen, and despite his topsy-turvy second half -- he compiled a 5.34 ERA and was tagged for an .802 opponents' OPS -- the Astros saw enough value to include him on their postseason roster, for situations such as Tuesday.

“It's big,” Greinke said. “It's an important part. I mean, great group of guys here. Some of the best guys that I've been around, and it's an important game, so I'll do what I can and hopefully help us out.”

Cristian Javier will be just as big of a piece for Houston on Tuesday, too, especially since Baker avoided using him on Monday. Depending on circumstance, Javier will likely follow Greinke, especially if the game is close.

Javier, a former starter, pitched two scoreless -- and critical -- innings during Houston’s Game 1 win, striking out four of the seven batters he faced after Framber Valdez stumbled through just 2 2/3 innings and Baker needed to go to his bullpen early.

Javier can also give Houston multi-inning length one day after it was forced to use five relievers.

“He was available [Monday], so he'll be even more available [Tuesday],” Baker said.