day.United are currently 10 points below the top four in the Premier League, meaning that they are likely to need to win the Champions League in order to qualify for next season's competition.
In recent weeks they have lost 3-0 at home to both Liverpool and Manchester City -- their ninth and 10th defeats of the campaign -- and are already certain to record their worst points tally of the Premier League era.
Their home form has been impressive in the Champions League, however, and with United having beaten Olympiakos 3-0 to overturn a two-goal deficit in the last 16, Guardiola says that they must not be treated lightly.
"We play against Manchester United -- one of the most important clubs in the world, regardless of the current situation," he said during Monday's pre-match media conference in Manchester.
"I know in the depth of my heart which team we are going to play against
Maybe they don't make a good season in the Premier League, but they did very well in the Champions League.
"And when I see (Wayne) Rooney, when I see (Rio) Ferdinand, when I see (Nemanja) Vidic, when I see Ryan Giggs, when I see (Danny) Welbeck or Chicharito (Javier Hernandez), I know them very well
I know the quality of these players.
"Maybe they played no good during the season
I don't know why, because I am not here (in England), but for one game or two games, they can make the best performance of the season
They can beat us
That is the truth."
Despite losing 3-2 on their last trip to Old Trafford in 2010, Bayern prevailed on aggregate to reach the semi-finals, but midfielder Bastian Schweinsteiger is troubled by his memories of that evening.
"On our last visit to Old Trafford, when we lost, the first 20 minutes we were under a barrage from the home side, driven on by their fans," he said.
"That experience of Old Trafford is in our minds
We will be ready tomorrow (Tuesday)
It will be a tough game, I am sure."
- Sympathy for Moyes -
Like his United counterpart David Moyes, Guardiola took over at Bayern at the end of last season, but while he has guided the Bavarians to a successful Bundesliga title defence in record time, Moyes has floundered.
Guardiola said that he felt for the Scot, whose position has come under heavy scrutiny, but he does not believe that United made a mistake by hiring him.
Asked if he sympathised with the former Everton manager, Guardiola replied: "Of course
Good things or bad things can happen to all the coaches around the world
I know it can happen to me tomorrow.
"Nobody has the secrets for eternal success
I have a lot of respect for my colleagues and when Manchester United decided to take David Moyes, it is because they are able to do it.
"Sometimes you need a little bit more time, but the decisions of Manchester United are always right
They believe he is a good coach and he made a good job at Everton."
Guardiola also took issue with a reporter's suggestion that Moyes's predecessor, Alex Ferguson, was partly to blame for the club's current predicament.
"I don't know how Sir Alex Ferguson can have a bad influence on this club," said the Catalan, who coached Barcelona to victory over United in the Champions League final in 2009 and 2011.
"I think it's completely the opposite
This club was the best club in England thanks to him
He re-organised the club and put the club on another level in this country."
Bayern will be without Brazilian centre-back Dante on Tuesday due to suspension, while midfielder Thiago Alcantara is unavailable after damaging knee ligaments in Saturday's 3-3 draw with Hoffenheim.
Source : AFP
Source: AFP