Club World Cup still has a lot to offer (the most exciting part, with the round of 16, quarter-finals, semi-finals, single-match knock-out). Anything can happen. However, if we look at the group stage, there's only one team that has won every single match: Manchester City. Quite a turnaround from what has been widely considered a bad, trophy-less season.
Three solid victories: 2-0 vs. Wydad AC, 6-0 vs. Al Ain, and perhaps surprisingly, 5-2 vs. Juventus, in a match with 77% ball possession, 24 shots, 11 on target, vs. 5 shots, 2 on target by the Italians. Guardiola's rival could be Salzburg, Al Hilal... or Real Madrid again.
No other team, among the 32 participant clubs, has won all three group stage matches. I'm writing this before the conclusion of Group H, with Real Madrid, Salzburg, and Al Hilal still with mathematical options, but none of them could match Manchester City.
Unsurprisingly, Manchester City also has the most goals scored (13) and better goal average (11). Only Bayern Munich comes (very close), with 12 goals and 10 goal average, but one defeat against Benfica that meant they are group runner-ups (they will avoid Chelsea and play against Flamengo in round of 16, so that's really a blessing in disguise.