Toronto Blue Jays fans are going to have to wait a little longer for the arrival of top prospect Vladimir Guerrero Jr.

Guerrero, who was placed on the Double-A disabled list earlier this week after getting hurt while running the bases, has been diagnosed with a knee injury that will sidelined him at least a month.

Keep in mind that it's four weeks until Guerrero is reevaluated, not four weeks until he returns to game action. It's possible he will be sidelined even longer and potentially miss the 2018 Futures Game during All-Star Weekend.

Vlad Jr., who is still only 19, was hitting a stout .407/.457/.667 with 11 home runs and nearly as many walks (20) as strikeouts (21) in 53 Double-A games before the injury. He is more than five years younger than the average Eastern League player. currently ranks Guerrero as the second-best prospect in baseball behind Atlanta Braves outfielder Ronald Acuna. Here is a snippet of their scouting report:

Much like his father, Vlad Jr. has an elite ability to barrel the ball from the right side of the plate and generates effortless plus raw power to all fields with his combination of bat speed, physical strength and hand-eye coordination ... Moved from the outfield to third base before the season, Guerrero shows glimpses of becoming a passable defender there in spite of having below-average speed and range ... As a future plus hitter with at least 30-homer potential, Guerrero boasts the offensive profile of a perennial All-Star and possible MVP candidate in his prime.

The Blue Jays have resisted called up Vlad Jr. in recent weeks even though third baseman Josh Donaldson has been on-and-off the disabled list and DH Kendrys Morales hasn't hit much this season. It's not unprecedented for a 19-year-old to jump from Double-A to MLB, but it is certainly rare. And Guerrero is very much a rare talent. 

The knee injury means Vlad Jr.'s call-up will be delayed a little bit longer, however.