Atlanta United and the Philadelphia Union are meeting for the third time this season on Sunday, but for the first time in the current MLS campaign. Both of the first two clashes took place in the CONCACAF Champions League, with Atlanta logging a 3-0 home loss, and a 1-1 away draw to the Union. This time around key injuries and absentees — due to Copa America — could see Jim Curtain and Gabriel Heinze switch up their tactics now that the two sides are familiar. Here, we will run down the major missing pieces, and what it means for both sides.

Atlanta’s losses

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The Five Stripes have two Venezuelan players at the 2021 Copa America: striker and talisman Josef Martinez, and yet-to-impress right back Ronald Hernandez. Injury-wise, wingers Machop Chol and Jürgen Damm both suffered leg injuries in early May, but neither seemed particularly serious. Both of these players, while not preferred, could play in the center where Josef typically lines up.

A more apt attacking replacement, Lisandro Lopez, has stepped away from the club after his father passed away.

The other prominent omission will be Emerson Hyndman, who tore his ACL in training, and will miss the remainder of the season.

Philadelphia’s Losses

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Another Venezuelan lost to Copa America, but this one’s for the Union. Jose Martinez’s shoes as the no. 6 will be difficult to fill.

Daniel Gazdag was meant to play at the Euros with Hungary, but was forced to return after citing a knee problem.

On the injury side, Jack de Vries went into concussion protocol in April, and MLS veteran Ilsinho has also been nursing a groin injury since April. Both of these players prefer to play in the right side of Curtain’s midfield diamond, however, neither are preferred over Alejandro Bedoya, but it is a sign of a potential issue in depth over that spot.

Atlanta’s tactical dilemma

To really pinpoint who is going to replace Josef Martinez as Atlanta’s central forward depends heavily on which of Heinze’s two formational favorites he will go with. First, let’s consider the 3-4-2-1:

The 1-1 draw against Seattle provides a great example for this style. Here, Martinez lines up as the furthest man forward, but behind him are Marcelino Moreno and Erik Lopez. Both of these two players are tucked inside, and the push beyond Martinez in transition in order to create a man-for-man situation on all three of Seattle’s center backs. This formation appears to be Heinze’s counter for wingback systems that attack more often than they defend; not something likely to come from Philadelphia.

The other, more traditional, 4-3-3 has an inverted triangle in the midfield and Santiago Sosa sits as the Regista. The wingers are typically inverted — although that’s not a requirement of Heinze’s — and the striker plays as high as possible and is often a target on counters and crosses.

Looking at this style in Atlanta’s second match against Philadelphia, Martinez is incredibly isolated.

Excluding the entire question about how Hyndman is going to be replaced, this system seems like the most viable option. The main issue now is that the leading strike options are Erik Lopez and probably homegrown Jackson Conway. Now, in this system Conway’s play style matches the demands that Heinze has set for Martinez, but it is undeniable that Lopez is just the all-around better option.

With that in mind, Heinze will most likely blur the lines between the no. 10 and the front three, and he will probably give the fullbacks autonomy to bulldoze into the attack. Here, in Atlanta’s 3-0 loss to Philadelphia, is what that may look like.

Onto the Union

Jim Curtain is unlikely to move away from his favored 4-1-2-1-2. He knows that its balanced midfield, and two strikers get the most out of his team.

As previously mentioned, the only real cause for concern is the no. 6 spot in that diamond typically filled by Jose Martinez. In Philadelphia’s last match — a 3-0 win over Portland — Curtain threw Leon Flach into the role as a quasi-test before Martinez had to leave. Flach, who typically lines up on the left, was replaced late in that match by Paxten Aaronson, allowing Martinez back into his natural role. On the other side of the diamond Quinn Sullivan replaced Ale Bedoya. Aaronson and Sullivan are both just 17.

Another, and more probable, option which Curtain used against DC United was moving Matt Real — a left back by trade — to the left side of the diamond after moving Flach to the no. 6:

Curtain knew he would have to rotate, and he has done a great job at getting different players into those roles he knew he would need. The issue he may face against Atlanta is the lack of depth out wide when the fullbacks and wingers start occupying the same areas.