Chaves cruised to a 4-1 win over Nacional in the Primeira Liga on Sunday but the game is more likely to be remembered for assistant referee Jorge Cruz getting caught short during the second half.
Cruz had to rush off to the toilet shortly after the interval, much to the amusement of players and fans alike.
After a few minutes' delay, Cruz was applauded back onto the field but if he thought he was going to get away lightly, he was sorely mistaken.
Referee Luis Godinho added to his fellow official's embarrassment by waving a symbolic red card in his direction.
Chaves - for whom William scored a hat-trick - and Nacional remain in trouble at the bottom of the table, with both in the relegation zone with three games remaining.
