One of the first rules you probably learned when you played football as a kid was that you have to play the ball forwards when kicking off.
And that's why the start of the match between Spain and the Czech Republic left everyone thoroughly confused.
For a lot of fans it was a proper double-take moment.
Have I missed rule change in football? Spain had one person at kick off and kicked it backwards? Am I being thick or did nobody notice that?
-- Nick Gearing (@NickGearing1) June 13, 2016
-- Dan Roberts (@danroberts92) June 13, 2016
Did Spain just play the ball backwards from kick off? I could of sworn the ball has to be played forward or has that rule changed?
-- spencer neil george (@SpenGee) June 13, 2016
But yes, as most people guessed, there has been a rule change.
BREAKING: Spain take advantage of the new laws by doing a one-man kick-off and knocking it straight back. Looked weird.
-- Daniel Storey (@danielstorey85) June 13, 2016
It is one of a number of new rules brought in for the tournament, so also look out for players getting sent off before the start of the game. That'll really confuse people.
Of course, this kick-off business is old hat to fans of the England's women's team.
-- Leigh Moore (@Leigh_Moore) June 13, 2016
Trailblazers, those Lionesses.