Bielsa's troops made the footballing world sit up and take notice by dominating both legs of their last 16 tie with the reigning Premier League champions as they cruised to a 5-3 aggregate win over the English outfit.
Guardiola though is a long-time admirer of the Argentine's methods, and was not in the least bit surprised by Athletic's remarkable performances at Old Trafford and San Mames.
"Bielsa is currently the best coach on the planet," the Blaugrana coach told reporters at a press conference on Friday. "We're lucky to have him in La Liga so that we can learn from him.
"[Bilbao's] qualification [for the quarter-finals of the Europa League] is a gift for the game."
Guardiola also admitted that he is looking forward to pitting his wits against Bielsa in what he believes will be a "wonderful" Copa del Rey final clash with Athletic at the Vicente Calderon in May.
Bielsa, of course, has been touted by some as the ideal successor to Guardiola, should the former Spain international elect to part company with Barca when his contract expires at the end of the season.
The speculation over Guardiola's future only seems to intensify with each passing day and he admitted that he feels bad that his players are regularly having to answer questions about the issue.
"I have to admit I feel a bit ashamed about the players always praising me and asking for my renewal," he confessed.
"Messi said that I was more important to Barca than him? Let's never forget people come to see Messi, not to see me."
It was recently reported that Guardiola had given his word that he would extend his stay in Catalunya but he denied that to be the case, stating: "No, I didn't say that to the club."
Guardiola has won 13 titles since taking charge of Barca in 2008.
Since November, Goal.com has been publishing exclusive extracts from Graham Hunter's highly-anticipated new book, 'Barca: The Making of the Greatest Team in the World'. The very last extract, which was published last Friday, looks at Andres Iniesta's risky return from injury in the 2009 Champions League Final and how he was described by Wayne Rooney as the 'best midfielder in the world'. Don't miss it!