He said: "[United are] a very good team. Obviously they've got a good manager, a fantastic stadium, and they're one of the favourites to win the Europa League but, as they say, 'Manchester is blue' and that's how it will be when we visit there as well, because we are Celta Vigo and we will try to keep the city blue."
Guidetti will now get the opportunity to make good on that promise after seeing Celta suffer a 1-0 defeat on home soil.
They have it all to do at Old Trafford in order to reach the final, but their 25-year-old frontman insists there is little to choose between the two teams in terms of quality.
He told Marca : “It was difficult for both teams. It was a very tough game and both defended very well.
"After the goal we hardly played a minute as they stopped playing football.
“They have lots of experience and it’s going to be difficult.
“They were not far superior from us and we were close so it’s not impossible.”
Marcus Rashford’s stunning free-kick separated the two teams in a tight first-leg encounter, with United heading back to Old Trafford with a narrow lead and a priceless away goal.