Benfica president Rui Costa was forced to back under-fire manager Roger Schmidt after their German boss refused to apologise to fans for their catastrophic 5-0 pummelling from Porto, ahead of their Euro showdown with Rangers.

Rangers travel to Lisbon this week for the first leg of the Round of 16 Europa League tie.

Both sides lost at the weekend and while Rangers' 2-1 home defeat to Motherwell was a surprise, Benfica's humbling at rivals Porto has seen the knives out for Schmidt.

The defeat was so embarrassing for Benfica, their social media accounts stopped posting the score after Porto netted their fourth goal and refused to post the final score.

And Schmidt hardly endeared himself to outraged fans after the game.

He said: "I'm not here to apologise. It's not as if we lost on purpose.

"The players have played so many good games, today wasn't our day, but the players prepared in the best way possible, sometimes football is like that and we have to deal with this situation.

"We have to show a reaction on Thursday against Rangers.

READ MORE: Tavernier demands reaction to loss as he urges Rangers focus

"Look, we lost in the first day of the season and that was out first league defeat since then. Winning at Porto is very difficult.

"I promise I will try to make our fans happy again."

However, Benfica quickly wheeled out legendary president Costa to address the fans. The 96-times capped former Champions League winner with AC Milan said: "I want to apologise to all Benfica fans for this night that didn't meet our club's high standards.

"I would like to thank the Benfica fans for the support they gave, especially those who were at the stadium, from the first to the last minute, they were tireless. Neither they nor anyone else deserved a defeat of this magnitude. As president, I take responsibility.

"We have to draw a lot of lessons, I won't say it's a night to forget, because we have to understand what happened, but at the moment we are still fighting on three fronts. The title was not lost today.

"We have to react quickly, as early as Thursday against Rangers.

"I understand the manager's comments, because obviously what he said is logical. As a former player, I know when players have a disastrous night like this, they don't do it on purpose."

And Benfica's horror night got even worse when key defender Alexander Bah was injured before the game with the Danish international right back now a major doubt to make the game against Rangers.