Real Madrid have begun the hunt to claim the Spanish Cup from Barcelona following the victory over third-tier side Fuenlabrada in the first leg of their fourth-round tie.
The Segunda B club resisted admirably before Fran Garcia brought down 18-year-old Achraf Hakimi.
Marco Asensio coolly converted from the spot, but replays suggested the foul was actually just outside the box.
Paco Candela then hauled down Theo Hernandez at a corner, with Lucas Vazquez stroking in from 12 yards.
Canedela was sent-off his foul on the Madrid left-back – it was his second yellow card in the seven minutes he spent on the pitch after coming on as a substitute.
And with two minutes to play, Madrid’s Spain Under-21 centre-back Jesus Vallejo was also sent off – a straight red card for a lunging challenge – on his debut for the club.
Madrid boss Zinedine Zidane made six changes from Sunday’s 3-0 win over Eibar, with key players such as Cristiano Ronaldo rested.
Barcelona have won the Spanish Cup in each of the past three seasons. They began their defence with a 3-0 first-leg victory at third-tier Real Murcia on Tuesday.
Zidane has never won the Copa del Rey as a player or a manager. As a player, he finished runner-up in 2002, when Madrid lost to Deportivo la Coruna, and in 2004, when they lost to Real Zaragoza.
The second legs are currently scheduled for 29 November. Real Madrid have not won the Copa del Rey since 2014