Barcelona defender Jordi Alba was hit on the head by a linesman's flag during the first half of Wednesday night's Copa del Rey clash with Atletico Madrid.
The 25-year-old full-back was brought to his knees after the assistant accidentally struck the Spaniard on the touchline as he ran back onto the pitch after ushering the ball out of play for a throw-in.
Alba actually knocked the flag straight out of the official's hand following the unfortunate collision midway through the first half, and pictures showed him in a considerable amount of pain as he rolled around on the floor.
It was already a lively start to the quarter-final second let at the Vicente Calderon after Fernando Torres gave Diego Simeone's side an early lead inside the first minute with another well-taken strike from the edge of the area to take his personal tally to three goals since returning to Madrid earlier this month.
Neymar was quick to draw Barcelona level after a swift counter-attack re-established the Catalan giants' narrow aggregate lead, but then Raul Garcia put the hosts back in front after converting from the penalty spot to make it 2-1 on the night and the two-legged tie 2-2 overall.
However, minutes later and the visitors restored parity again thanks to an unfortunate own goal by Miranda before Neymar netted his second of the game to put Luis Enrique's men 3-2 up in the first half and extend their aggregate lead to 4-2 at the interval.