The 2026 FIFA World Cup was the first to mandate hydration breaks, brief stoppages near the twenty-second minute of each half, in every match regardless of weather. A widespread claim holds that these breaks blunt the momentum of whichever side is dominant. We test the claim with a within-match case-crossover design, using non-break minutes of the same match as self-matched controls. This differences out every match-level characteristic and adjusts only for game time, scoreline, and pre-break momentum state. The apparent post-break fade is not caused by the break. The dominant side's momentum decays at essentially the same rate whether or not a break occurs, so momentum reverts through the stoppage as if play had continued. What the break removes instead is the continuation of that side's pressure during the stopped minutes, and this removal leaves no trace in net expected goals. We define the target as a case-crossover effect on the treated, local to the observed break minutes. The average effect is only weakly identified, resting on a time-trend extrapolation into a window with no untreated minutes, whereas break-by-covariate interactions are stable. The average effect itself is small and near zero. With only 99 matches, however, the design lacks the power to reject a small effect, so we read the results by effect size and compatibility interval rather than by statistical significance. The estimates are not uniform across match states: for a comfortably-leading side of average strength the implied effect is a momentum loss (near (-4) points on a pre-break level of about +20). We report this state-dependent signal as exploratory and in need of replication.
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