CLEVELAND -- Nine days ago, Will Brennan wasn’t even on the Guardians’ roster.

It’s not like the team’s No. 20 prospect, as ranked by MLB Pipeline, hadn’t earned the right to get his shot in the big leagues yet. He’d been raking in the Minors all season long. But the Guardians thought it was best to give Brennan as long of a chance as possible to play on an everyday basis before coming up to the big leagues and getting more sporadic playing time.

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Nine days later, and Brennan is already making a convincing case to not only be in the lineup every day, but to take a spot on the postseason roster.

Brennan was on the bench for the first 7 1/2 innings on Thursday night before he was called on to pinch-hit for catcher Austin Hedges to lead off the bottom of the eighth. On the third pitch he saw, he smacked a hard ground ball through the right side of the infield that sparked a two-run inning to give the Guardians a 2-1 victory over the Rays at Progressive Field.

“I think the biggest thing is just getting your body ready,” Brennan said. “I pinch-hit a couple times in High-A, and that was probably the last time I pinch-hit. I thought back to my Spring Training at-bats when I’d come in big league games and pinch-hit and I think, ‘Just be ready from pitch one. Just go up there, don’t be intimidated, just go up there and do your thing.’”

Just stepping in the batter’s box without feeling any intimidation has been a common theme among the 16 rookies who have debuted for the Guardians this season. Starting with Steven Kwan on Opening Day, hardly any young player who got his first shot in the Majors this season has looked overwhelmed on the big stage. Brennan isn’t any different.

Brennan started the year with Double-A Akron, but after owning a .311 average and an .886 OPS with 12 doubles, four homers and 39 RBIs in 36 games, he received a promotion to Columbus. The 24-year-old outfielder didn’t let up, as he batted .316 in Triple-A with an .838 OPS, 28 doubles, three triples, nine homers, 68 RBIs, 15 stolen bases, 33 walks and 53 strikeouts in 93 contests for Columbus. His consistency made it impossible for the big league club to ignore him.

“I can’t believe that Columbus lost a game this year,” Guardians starter Cal Quantrill said. “Will, just like the rest of the guys who came up, it’s a professional at-bat. They’re ready to hit and don’t look overmatched. … It’s a big league approach. It really separates them from other rookies.”

Since his debut just over a week ago, Brennan has quickly made an impact, going 8-for-24 (a .333 average). The Guardians have mostly played him when a right-hander is on the mound, and the lefty hitter has thrived -- and thrived to a point that it seems likely that a player with just seven big league games under his belt will make Cleveland’s postseason roster.

As a quick refresher: Anyone who was in the Guardians’ organization AND on the 40-man roster before Aug. 31 is eligible to make the postseason roster. Although Brennan was in the organization, he wasn’t yet on the 40-man roster by the cutoff. However, as long as a player was in a team’s system before Aug. 31 (like Brennan), he can replace an injured player in a club’s postseason eligibility pool. That means Brennan could be used to replace Anthony Gose.

The only reason this could get a little confusing is because the Guardians just added No. 5 prospect Bo Naylor to their taxi squad for the time being. There’s a chance the team would consider him to make the postseason roster, as well, to add more catching depth to its roster. However, with only one injured player, the team can add only one of these two young prospects to replace Gose, unless another injury occurs.

It might be a difficult decision to get the best players available on their playoff roster. But the Guardians certainly can have confidence in going with Brennan, if they’d choose to do so.

“I think he wouldn’t be here if we didn’t think he could help us win,” Guardians manager Terry Francona said. “With three weeks to go in the season, we’re not gonna call guys up that we think [can’t help us]. … We’re trying to win. So I think that’s about the biggest compliment we can give him.”