We’ve barely noticed how well the U.S. back line has played in this tournament, what with distractions like Pulisic’s injury watch, Balogun’s B.S. red card, and a blizzard of American goals. Yet Pochettino’s back three has been superb because it works specifically in context of our midfield five. We may have to shut out the Belgians to advance Monday, and so this rear-guard alchemy is critical.

Many media outlets, even the Federation’s USsoccer.com, have referred to the starting formation vs. Paraguay as a 4-2-3-1, but it’s better understood as a 3-5-2, with Dest flanking a midfield triangle of Adams-McKennie-Tillman. Dest has full license to go forward; he’s an old-fashioned, box-to-box winger.

Robinson, on the left? Not so much. Though he traditionally rampages up and down the left flank with great enthusiasm, Jedi has stayed more at home this summer — so he might better cover the ass of Old Man Ream.

Have you noticed that most teams in this tournament have a skilled, superannuated dude who can go an hour, maybe the whole game if need be? Thirty-eight-year-old Tim Ream is our Modric/James/Džeko/Ronaldo/DeBruyne. The FC Charlotte centerback is there for distribution, not necessarily man-marking prowess. With Richards healthy and masterful, with Freeman growing every day, with Jedi by his side, Ream has appeared old and slow only a few times in this tournament.

But how, without Balogun, do we score goals than we allow Monday night vs. Belgium.

Pochettino has shown creativity and bravery realigning in response to injuries, bans and opponents. No one saw the Balogun-Pepi pairing vs. Australia coming, for example. No one anticipated a back four vs. Turkiye. But Poch realized it was better suited that B Team, dead-rubber defensive corps: Trusty, Miles Robinson and Mackenzie.

Poch trusts his players to adapt and Balo’s absence vs. the Belgians could reveal another curveball from the Argentinian.

Expect Pulisic, on the left, to pair with Pepi — perhaps as more of a second striker. They’ve frequently and effectively played together up front, side by side. We might see Hadji Wright if the first hour is scoreless.

Or, we might see Tillman pairing with Reyna, which would oblige McKennie to stay a bit more at home, beside Adams.

Ahead of the Australia, I thought Poch revealed an interest in playing these two attacking midfielders together, in a fluid threesome with McKennie. Why? Possession, in spades — with Tillman feeding a marauding Dest down the right. This roster is awash with attacking midfielders of quality; Aaronson and Zendejas are pretty darned good, too. In adjusting to new circumstances, clever managers lean into squad strengths.

The elephant in the room ahead of Monday’s Round of 16 tilt is, of course, the Belgians’ 5-2 dismantling of the U.S. back in March.

The USMNT actually played a solid, enterprising first half and took a 1-0 lead in Atlanta before falling apart after halftime. Ream looked old and slow as part of a back four that included neither Alex Freemen nor Chris Richards. Doku tortured the U.S. defense up and down either wing.

The World Cup group stage completely transformed this USMNT. Meantime, the Belgians finished third in weak group, scraped by Senegal in the R32, and DeBruyne has been more Džeko than Modric. This feels like a team on the verge of major transition, not a World Cup quarterfinalist.

Dodi Lukébakio (no. 14 above) is a promising young striker. He scored twice in the March friendly, but he’s proved a non-factor this summer. His only action? Against Iran, when he came on after an hour. Eight minutes later Nathan Ngoy got sent off, forcing a reshuffle that left the Benfica man isolated and ineffective.

The re-emergence of Lukaku — who has played more minutes in this Mundial than he did all year long for his club, SS Napoli — underlines the fine line coach Rudi Garcia is walking. Will this team will live and die with its aging skill players, even if it means limited minutes? Or will Garcia go with the kids?

DeBruyne has gone off after an hour in every match so far. Lukaku has come off the bench. I expect starter minutes for the former Chelsea man Monday, at the expense of Lukébaki and young Charles de Ketelaere.

At this World Cup, the U.S. has not yet seen a striker like Lukaku. He’s frankly got few comps anywhere in the word when it comes to speed, power and touch. He’s old. Neither is he fit, but he remains a handful. Youri Thielemans, 29, is the only Belgian of high quality in his prime. The Villa man almost single-handedly beat Senegal, and he took over only after de Bruyne went off.

If the U.S. can find a way to neutralize Thielemans and Doku, a single goal could win the match.