The group stage of the FIFA World Cup is one tournament, and the knockout stages is another. The group stage allows for teams to bounce back from a poor result, while once in the round of 16 it’s win or go home.
Uruguay in 2014 was able to bounce back from a terrible first match against Costa Rica losing 3-1. La Celeste would defeat England and Italy to eventually get knocked out by Colombia in the round of 16. The USMNT was able to use their first game draw against England in 2010 to leverage winning the group with their last-minute goal against Algeria.
Many teams after their first game will be using a calculator and review scenarios to stay alive at the World Cup. Since 1998 the following is the percentage teams have to qualify from the group stage after winning, drawing, or losing their first game.
Round of 16 chances after first match
A win in the first game of the tournament gives teams an astonishing 83.6% chance of advancing. Few teams fail to qualify for the round of 16 after a win in game 1 of the group.
A draw and the chances drop substantially but still in said teams favor, 58.7% chance of advancement since group stage has been determined by the top two of each group.
To lose an opening round game is almost a death nail, only 11% of the time has a team that dropped their first match come back to qualify from the group.