Benfica, who are third in Portugal’s Primeira Liga, host the first leg of the tie at the Estadio da Luz on Tuesday at 20:00 GMT.
The Portuguese side looked to be heading out of the competition on goals scored, despite leading Madrid 3-2 with seconds remaining.
But Benfica were awarded a free-kick against nine-man Real, who had Raul Asencio and Rodrygo sent off in added time, and Ukraine goalkeeper Trubin headed past opposite number Thibaut Courtois.
Mourinho said the tie will be “very demanding, without a doubt”.
He added: “Trubin won’t be in the attack at the Luz stadium. I’m very used to these kinds of ties.
“I’ve been doing it all my life. People often think you need a certain result in the first leg for this or that reason. I say there is no definitive result.”
The victory last month was Mourinho’s first over his former club and meant Benfica reached the knockout stages despite losing their first four games in the league phase.
Real, meanwhile, are top of the La Liga table, two points clear of rivals Barcelona in second place.
