Lewandowski was worshipped by Borussia Dortmund fans during a prolific spell with the club following his move from Lech Poznan in 2010, establishing himself as one of the best strikers in the world.
The Poland international will line up against Dortmund in the DFL Supercup on Wednesday, though, after opting to join Bundesliga rivals Bayern Munich when his contract expired at the end of last season.
"He is still a great guy. There will be plenty of hugs." Klopp said of Lewandowski.
Dortmund beat Bayern 4-2 in the Supercup last year to ensure Pep Guardiola's first competitive game in charge of the Munich outfit ended in defeat.
Bayern went on to win the Bundesliga title with ease before beating Dortmund 2-0 in the DFB-Pokal final in May and the champions will be eager to make a statement of intent when they renew their rivalries on Wednesday.
He said at a press conference on Monday: "We're taking the Supercup very seriously. We're desperate to win.
"Games against Bayern are always very special. They're one of the best teams in the world."
While Lewandowski can expect a warm welcome in midweek, Bayern chairman Karl-Heinz Rummenigge will not be quite such a popular figure if he makes the trip.
Rummenigge riled Dortmund by revealing that Marco Reus has a €25 million clause written into his contract, which comes into effect next year.
Dortmund chief executive Hans-Joachim Watzke reacted by stating that Rummenigge had only succeeded in increasing the tension between the two clubs ahead of the new campaign.
Dortmund's new captain Mats Hummels misses out due to a muscular injury, while Nuri Sahin, Jakub Blaszczykowski (both knee) and Ilkay Gundogan (back) are also sidelined.
Klopp, who must decide whether to start fit-again defender Neven Subotic, admitted his side had plenty of work to do ahead of the new season after they were hammered 4-0 by Liverpool on Sunday.
Bayern also have injury problems, with Rafinha (ankle) and Thiago Alcantara (knee) among the absentees while Guardiola has a concern over Franck Ribery (knee).
The likes of Manuel Neuer, Thomas Muller, Bastian Schweinsteiger and Philipp Lahm started on the bench in a surprise 2-1 defeat against the MLS All-Stars last week and could all come back into contention.
Guardiola was left fuming with some robust challenges from the All-Stars, who come from behind to secure victory after Lewandowski had opened the scoring.
