The MLB rosters expanded to 40 players on Tuesday, which gives clubs the luxury of promoting some prospects with hopes they make an impact down the stretch. The Chicago Cubs called up Javier Baez, who spent 52 games with them last season, and he's expected to play an integral role with the team.

Baez is perhaps the most notable call-up due to his previous MLB experience as well as the success he's had this year. The 22-year-old has rebounded from his inauspicious performance that spanned from last August through spring training and batted .324/.385/.527 with 49 runs scored, 13 home runs, 61 RBIs and 17 stolen bases in 70 games at Triple-A Iowa this year.

"He's in a good place," President Theo Epstein told Paul Sullivan of the Chicago Tribune. "He has earned his way and worked his way into this position to come up and contribute to a winning team."

Here are the rest of other young prospects who have already gotten the call to the MLB:

Joey Gallo, 3B/OF, Texas Rangers

Gallo already played 25 games with the Rangers this season when Adrian Beltre hit the disabled list. The 21-year-old was extremely impressive in his first few games, but he soon came back down to earth. He batted .218/.306/.448 with 13 runs scored, 5 home runs and 13 RBIs in 98 plate appearances and also struck out 43 times.

Texas is in the midst of a tight AL playoff race, so Gallo will likely contribute to their late season push.

Dalton Pompey, OF, Toronto Blue Jays

Pompey began the season with the Blue Jays after making his MLB debut last September. However, his struggles on offense forced the team to send him back down to Triple-A Buffalo in May (he was then demoted to Double-A in June). He had a good opportunity to solidify himself as the team's starting center fielder, but he failed to do so after batting .203/.276/.354 with two home runs and six RBIs in 79 at-bats.

Perhaps he'll see some more pitches in the new-and-improved Blue Jays' lineup and take advantage of his opportunity this month.

Marco Gonzales, SP, St. Louis Cardinals

The Cardinals called up Gonzales to make his 2015 debut last night against the Washington Nationals as the team planned to skip Carlos Martinez's start. It wasn't successful, but St. Louis got the win. The 23-year-old was 4-2 with a 4.15 ERA, 1.53 WHIP and 31 strikeouts in 10 games (five starts), totaling 34 2/3 innings last season, but dealt with shoulder issues in 2015.

Gonzales played a big role in the team's NLDS win over the Los Angeles Dodgers last year, which means he can earn a spot on the postseason roster if he proves himself in September.

Rob Refsnyder, 2B, New York Yankees

The Yankees promoted Refsnyder earlier this season to see how his skills would transition from the minors to the MLB. Well, his defense, which was a big concern in spring training, still clearly needed some work. He only got 12 at-bats and managed to hit a two-run homer against the Boston Red Sox.

He'll need to show he's improved his flaws this month if he wants a shot to remain a mainstay with New York.

Zach Davies, SP, Milwaukee Brewers

Milwaukee acquired Davies before the non-waiver trade deadline when they sent Gerardo Parra to the Baltimore Orioles. Davies will make his MLB debut tonight against the Pittsburgh Pirates after going 6-8 with a 3.30 ERA, 1.36 WHIP and 102 strikeouts in 24 games (23 starts), totaling 128 1/3 innings, between Triple-A Norfolk and Triple-A Colorado Springs.

He's expected to remain in the Brewers' rotation for the month of September.

Miguel Castro, RP, Colorado Rockies

The Rockies acquired Castro in the mega deal that sent Troy Tulowitzki to the Toronto Blue Jays. Castro appeared in 14 games for the Blue Jays (he's still only 20 years old) and was 0-2 with a 4.38 ERA, 1.70 WHIP and 12 strikeouts in 12 1/3 innings before being sent back down.

His debut with Colorado did not go well yesterday. He surrendered four earned runs on three hits and one walk in 1 1/3 innings against the Diamondbacks in a 6-4 loss. However, he has a high ceiling and should be part of the Rockies' future, with this month providing a solid preview.

Hector Olivera, 3B, Atlanta Braves

Read more here.

Stay tuned for more call-ups as we update this list throughout the week.