Nairobi, July 4. Atlanta in July carries a particular kind of heat, the sort that settles into a stadium and stays there through the evening, and it is into that heat that Argentina and Egypt walk on Tuesday for a Round of 16 tie that neither nation’s recent history quite prepared it for in the same way. Argentina arrive as world champions defending the title on American soil. Egypt arrive having never won a men’s World Cup knockout match before this tournament. Kick-off at Mercedes-Benz Stadium is 16:00 UTC, 12:00 PM ET, 17:00 in the UK, 9:30 PM in India, and both facts, the holders’ pedigree and the debutants’ novelty, will be tested at the same clock.

Argentina’s route to Atlanta is, on paper, the tidiest in the competition. Per FIFA’s official match centre, they won Group J with nine points from three matches, scoring eight goals and conceding one. It opened with a 3-0 win over Algeria in which Lionel Messi scored all three, continued with a 2-0 win over Austria in which Messi scored both, and closed with a 3-1 win over Jordan, Giovani Lo Celso, Lautaro Martínez and Messi sharing the goals. The Round of 32 was a different proposition entirely: a 3-2 win over Cape Verde that needed extra time, Lisandro Martínez and Messi scoring the goals that separated the two sides. Eight goals from four matches, seven of them touched by Messi in some way, and a single goal conceded all tournament, that goal coming from Cape Verde in a match that had no business being as close as it was.

Egypt’s path has been longer to describe and shorter on comfort. They finished second in Group G with five points from a 1-1 draw with Belgium, Emam Ashour scoring; a 3-1 win over New Zealand, with goals from Mohamed Salah, Mostafa Zico and Trézéguet; and a 1-1 draw with Iran, Mahmoud Saber scoring. The Round of 32 brought Australia and another draw, 1-1 after extra time, Ashour scoring again, before Egypt won the penalty shootout to reach the last sixteen. Five goals and three conceded across four matches, and a group of players who have now won a World Cup knockout match for the first time in the nation’s history, by way of a shootout rather than a rout.

The ranking gap between the two sides, FIFA’s world ranking placing Argentina third and Egypt twenty-ninth, is the largest of any tie in this round, and it is the kind of gap that world champions have learned not to fully trust. Cape Verde, ranked far below Argentina themselves, took the holders to extra time three days ago with two goals of their own. Lionel Messi has been asked about margins like that before, and after the Cape Verde match he told ESPN, “As this team has demonstrated many times, and as I’ve said many times, it competes. And we competed to the end.”

It is not a statement about Egypt, who Messi has not yet played at this tournament, but it is a fair description of the task in front of Argentina now that the group stage’s comfortable arithmetic has given way to knockout football, where a single goal conceded against Cape Verde already outweighs the one conceded across three group matches. Egypt’s own knockout education has come the hard way too, through two consecutive draws that both went to shootouts or extra time rather than a single settled ninety minutes, and a squad that has learned, in real time, what it takes to survive a match it is not winning outright.

Neither team has faced the other’s specific shape yet, which is the honest state of every last-sixteen tie before it is played. Argentina have not faced a defence set up the way Egypt’s has been across four matches that produced only five goals against them. Egypt have not faced an attack that has scored eight times with one man responsible for seven of those touches. What both teams share, going into Atlanta, is recent proof that this tournament punishes comfort: Argentina’s own group form did not carry cleanly into the Round of 32, and Egypt have not won a single match in ninety minutes since the tournament began. The Round of 16 bracket will have one fewer name in it by Wednesday morning in Nairobi, and neither of these two nations’ World Cups so far tells you, with any real certainty, which name that will be.