Before rallying to down the Mets on Monday and extend their lead in the NL East, the Nationals were reeling.

They had lost seven of their last eight games and ace right-hander Stephen Strasburg was just placed on the disabled list with a back issue. That's rough.

Strasburg's injury means the Nationals need a spot starter for Tuesday's game, and Monday afternoon, manager Dusty Baker told reporters the team will go with top prospect Lucas Giolito. He's going to be called up to make his MLB debut.

Giolito, 21, is skipping right over Triple-A. He has a 3.17 ERA with 72 strikeouts in 14 starts and 71 innings for Washington's Double-A affiliate this year. Obviously the Nationals believe he is ready to handle the assignment and help them win a crucial intra-division game.

Here are four things to know about Giolito's call-up.

1. Giolito is the best prospect in the minors, pitcher or position player.

Coming into the season, Giolito was included in a group of four prospects considered the game's truly elite with Corey Seager, Byron Buxton and Julio Urias. Seager and Buxton have since graduated to the big leagues, and Giolito has passed Urias as a prospect, making him the game's No. 1 prospective big-leaguer.

Here is a snippet of's free scouting report on Giolito:

Giolito has the highest ceiling among Minor League pitchers, boasting an elite fastball that sits mid-to-upper-90s and a 12-to-6 curveball that he throws with power and hard, downer action. His changeup has steadily improved in the past two seasons and his confidence along with it, giving him a legitimate weapon against left-handed hitters ... The sky is the limit for Giolito, who has the stuff, physicality and command to develop into an ace.

That is some mighty high praise. The term "ace" gets thrown around way too often these days, but prospect hounds use it sparingly when talking about young kids in the minors. You have to be very special to get the "future ace" moniker, and Giolito is indeed special. Here's some video from spring training.

2. The Nationals drafted Giolito knowing he needed Tommy John surgery.

No high school right-hander has ever been drafted first overall, though Giolito was very much in the conversation in 2012. He came down with an elbow issue a few weeks before the draft, though, which scared teams away. The Nationals selected Giolito with the 16th pick, paid him a $2.925 million bonus, then sent him for Tommy John surgery.

Washington has shown a willingness to take risks in the draft -- they took UNLV righty Erick Fedde in the first round in 2014 even though he was rehabbing from Tommy John surgery -- and they've been rewarded with Giolito. They made the bold pick, were patient as he rehabbed, and now they have one of the best young pitchers in the game.

3. This is a big game for the Nationals.

The Nationals are not easing Giolito into things. They're throwing him right into the fire. Giolito will make his first career start against the division rival Mets, who are four games behind the Nationals and looking to close the gap in the NL East. The opposing starter? Matt Harvey, who is pretty much everything the Nationals hope Giolito will one day become. This will be quite a test.

Lucas Giolito, MLB's top pitching prospect, will face a big test in his MLB debut Tuesday night. USATSI

4. Giolito could force his way into the rotation for good.

Prior to the Strasburg injury, the Nationals had used only five starters this season: Strasburg, Max Scherzer, Gio Gonzalez, Tanner Roark and Joe Ross. Long man Yusmeiro Petit started for Strasburg on short notice last week, but that was an emergency. The team didn't have time to call anyone up because Strasburg was scratched that afternoon.

Scherzer and Strasburg aren't going to lose their rotation spots for obvious reasons. Roark and Ross have been very good as well. Gonzalez is the exception. He has by far the highest ERA (4.73) and WHIP (1.37) among the club's five starters, and it seems as though their patience is starting to wear thin. Once Strasburg returns, don't be surprised if the Nats look to keep Giolito around and send Gonzalez elsewhere before the trade deadline.