It has been an incredible year for rookies in Major League Baseball, with Juan Soto of the Washington Nationals, Ronald Acuna Jr. of the Atlanta Braves and Miguel Andujar of the New York Yankees all looking like seasoned veterans.

With rosters set to expand in September, Vladimir Guerrero Jr., the powerful son of the newly minted Hall of Famer, could get a chance to join those talented newcomers. And considering his production at every level of the minors, he might even put Soto and Acuna to shame.

Two other top prospects — Fernando Tatis Jr. and Nick Senzel — have suffered season-ending injuries, but more than a few other major league-ready players are biding their time at baseball’s lower levels.

Here are five players who, if and when they get the call, could quickly make themselves known to casual fans and fantasy baseball enthusiasts.

Vladimir Guerrero Jr., 3B, Toronto Blue Jays

A promotion to Class AAA slowed Guerrero, 19, a bit. Instead of hitting the .402 he was batting in Class AA, he is down to .345. But he also has a .448 on-base percentage and a .656 slugging percentage despite being 7.6 years younger than the average position player in the International League. He recently homered in four consecutive games, and while he is going to need to find a new defensive position at some point — he is not a gifted third baseman and he keeps getting larger, which will not help — he is clearly ready for the majors.

Eloy Jimenez, OF, Chicago White Sox

That Jimenez, 21, is still in the minors is a bit of a joke. He had a .317/.368/.556 (batting average/on-base percentage/slugging percentage) stat line in Class AA this season, then was promoted to Class AAA and somehow improved to .346/.388/.627. He has a combined 21 home runs a year after he hit 19 across two minor league levels, and his defense is passable for a player expected to be a middle-of-the-order star. He just needs the White Sox to admit he is ready.

Austin Riley, 3B, Atlanta Braves

The Braves have thrived by letting their kids play, as evidenced by the heavy load they have put on Acuna, Ozzie Albies and the recently promoted Touki Toussaint. Riley, 21, could be another Baby Brave to get his chance as he appears to have largely recovered from a knee injury that forced him out for about a month. The biggest red flag in his transition to the higher stages is that his power — he had 20-home run seasons in 2016 and in 2017 — took a fairly significant hit when he moved from Class AA to Class AAA.

Christin Stewart, OF, Detroit Tigers

Do not expect a high average — or passable defense — should Stewart, 24, get the call, but be ready for some fireworks: He has major league power. He has 79 home runs over the last three seasons and makes up for his low average in part with a decent number of walks. Detroit’s outfield, beyond Nick Castellanos, is fairly devoid of power. And with Stewart not getting any younger, the Tigers may want to see if he can be a power-and-patience answer (even if that means taking time away from the struggling Victor Martinez, 39, at designated hitter).

Victor Robles, OF, Washington Nationals

A hyperextended elbow that kept him out for three months this season has made it hard to tell if Robles, 21, had been struggling with the adjustment to Class AAA or if he simply was not right physically, but he looked like his old self Saturday when he went 4-for-6 in a win over the Columbus Clippers. He has taken a big step back statistically from last season, when he slashed .300/.382/.493 over two levels with 10 home runs and 27 steals. But even if his bat is not fully recovered, Robles has sufficient speed and defensive ability to make him a decent bet to be a full-time major leaguer should Bryce Harper depart, so letting him see more major league pitching sooner rather than later would be wise.