Happy with everyone
It certainly didn't prove easy at Ewood Park for Jose Mourinho's side, after Marcus Rashford managed to bring the sides level before the break after Danny Graham's opener.
It was looking to be heading for a replay at the Theatre of Dreams as the clocked ticked down, but a late strike from Zlatan Ibrahimovic saw them in the last eight.
It set up a tough tie against Chelsea in the quarter-finals, but Herrera stated that it was their character that saw them through their trip to Lancashire.
“I think we played very serious,” Herrera told MUTV, going on to add that “we can be very happy with the attitude of everyone."
"It's not always enough to come with a good attitude," the Spaniard admitted to the club's channel. "You must come with the best attitude."
“It is never easy to come here," the midfielder conceded after the clash. "Because the opponents in these types of games always play with everything to beat us."
"We have the quality so when the attitude is very good," Herrera added. "Sooner or later the goal will come.”
Fighting for trophies
This victory meant that the opportunity of a treble of domestic trophies was still alive, ahead of their second leg against St Etienne and the EFL Cup final against Southampton on Sunday.
The clash with Carlos Puel's side will be their first opportunity of silverware, and Herrera stated the Red Devils will be fighting for every title.
“That's what this club is about [fighting for trophies]," he said talking about Sunday's EFL Cup final. "We fight for every title, every trophy, respect our history and we are showing that in every game."
“Sometimes you can play better or worse," he stated. "But the attitude is always very good."
"We are in a good moment," Herrera concluded. "Hopefully we can continue like this.”
Manchester United will take on St Etienne in the last 32 of the Europa League at the Stade Geoffroy-Guichard on Wednesday, February 22 with kick-off at 5pm GMT.