FiveThirtyEight is examining each of the eight groups in the 2018 World Cup, which begins Thursday in Russia. Read about Group A, Group B, Group C, Group D, Group E, Group F and Group G. Group H is potentially the most interesting in Russia this summer. While the average group difference in FiveThirtyEight’s Soccer Power Index score between the best and worst teams is about 25, Senegal’s SPI rating of 66.0 is only 14.5 points lower than Colombia’s 80.5.