Bayern hold a commanding 3-0 lead following an impressive victory at Stamford Bridge in February, but they will not have played a competitive game in over a month when they take on the Blues at the Allianz Arena on August 8.
Goretzka thinks that gives Frank Lampard's side an edge, though the Bundesliga and DFB-Pokal champions will do their utmost to ensure Chelsea do not repeat their 2012 Champions League final success over Bayern in Munich.
"We've already had a great season, winning the championship and the cup," Goretzka told Bild am Sonntag . "It is clear to every one of us that the competition and our path to the final is extremely challenging."
Whoever progresses from the tie between Chelsea and Bayern will take on either Napoli or Barcelona in the quarter finals in Lisbon, with one of Real Madrid, Manchester City, Lyon and Juventus waiting in the final four.
Goretzka continued: "All our focus in on the game against Chelsea. The good thing about such top opponents is that they have as much respect for us as we do for them.
"Chelsea has the advantage that they are travelling to Munich just after the season, while we want to keep up our rhythm.
"We will do everything to make sure Chelsea will not be successful again in Munich."
The Bundesliga was the first of Europe's top five leagues to resume amid the coronavirus pandemic, with the campaign wrapped up on June 27. Goretzka impressed in the heart of Bayern's midfield following the resumption in May and put it down to increasing his muscle mass during the hiatus.
"For me, lockdown was both a crisis and an opportunity," said Goretzka. "A crisis because you miss football and daily training with the team, but also a chance to gain muscle mass in co-ordination with the physiotherapist.
"In crucial games and moments, it is important to be physically and mentally fit. The weight helps me in tackles, makes me a bit more agile and robust. Not only on the ground in a one-on-one, but also in the air."