In knockout football, control only counts if it turns into separation. Argentina eventually found that separation in extra time, and Alvarez was central to it.
That matters because semi-finals are often decided by the player who can turn a tight game with one action. Alvarez looks capable of being that player. A goal of that quality does more than settle a quarter-final; it sharpens belief across the squad.
If Argentina come in on a surge, England come in with a warning light flashing. Other reports say they needed extra time to beat Norway 2-1, with Jude Bellingham scoring both goals. Another update says Thomas Tuchel was unhappy with the overall display.
That gives the semi-final an interesting shape: England have a match-winner in peak form, but their route here suggests vulnerability. Argentina, by contrast, appear to be building rhythm at the right moment.
The obvious duel is star power against structure. Bellingham is carrying huge attacking weight for England, while Argentina now have fresh evidence that Alvarez can decide a game under maximum pressure.
The next storyline is simple: can England tighten up after a ragged quarter-final, or will Argentina ride the momentum of a dramatic 3-1 win into the final? On current evidence, this semi-final should be decided by fine margins - and by whichever big-name attacker lands the next big blow.