When Guardiola steps on to the Old Trafford turf on Tuesday night, many United fans will be wishing he was heading for the home dugout rather than the away one.
After winning the Champions League with Barcelona twice, Guardiola took a 12-month sabbatical before deciding to take the reins at the Allianz Arena.
Speculation was rife that Ferguson offered Guardiola the chance to succeed him at Old Trafford when the pair met for lunch in New York five months before the Scot announced his retirement.
Guardiola concedes he may have been given a chance to take the position at United, but the offer could have been lost in translation.
"He invited me to a super restaurant (in New York)," the Bayern coach said.
"It was a friendly dinner, like always. He was so gentle and we spent a very good time together.
"My English is not so good and when Sir Alex spoke quickly I didn't understand him so maybe I didn't understand if I received an offer or not!"
Guardiola's humorous attempt to dodge a question regarding the meeting in December suggests the topic of Ferguson's retirement did come up.
Guardiola has no plans to leave Munich any time soon, but when he does decide to move on, he will not be short of offers.
The Spaniard has enjoyed a stellar first season as Bayern boss, winning the Bundesliga in record time with seven matches to spare.
Bayern are unbeaten in the league and Saturday's six-goal thriller against Hoffenheim - in which Guardiola fielded a weakened team - was only their third draw of the season.
The man in the opposite dugout could not have had a more contrasting maiden year in charge of his new side.
David Moyes' team sit seventh in the Barclays Premier League, with almost no chance of finishing in the top four.
Guardiola is wary of the fact that United are underdogs in their own stadium, though.
"Last season Bayern won everything and this season we are over 20 points ahead of our opponents with seven matches to spare," Guardiola said.
"But I know in the deep of my heart which team we are going to play against. Maybe they haven't had a good season in the league but when I see (Wayne) Rooney, (Nemanja) Vidic, Rio (Ferdinand), Chicharito (Javier Hernandez) and (Danny) Welbeck, I see very good players. I don't know why United haven't played well in the league, but over one game or two games, they can beat us."
With Thiago Alcantara out through injury, more pressure will fall on the shoulders of Toni Kroos.
United have been heavily linked with a move for the midfielder, who is out of contract next summer, but Guardiola and Bayern chairman Karl-Heinz Rummenigge, say there is no chance of the 24-year-old leaving in the summer.
"Toni Kroos is sure to play in a Bayern Munich shirt next year as well," Rummenigge told reporters before flying to Manchester on Monday morning.
Guardiola echoed those words, but could not offer any assurances that the German would stay beyond next season.
"Toni has one year more of a contract and Toni will remain," Guardiola said.
"I hope he can extend his contract and stay with us because he is a very good guy, he loves his game, it is not just a job for him and I would like him to stay.
"I spoke with the player, with the club, I gave my opinion. After that I am not manager, I am just the trainer."
As well as Thiago, Bayern will be without Holger Badstuber and left-back Diego Contento, who are also injured.