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The Polish striker would hope to make his Bayern exit as painless as possible, after making it clear to the club he is determined to move on before the new campaign starts.
That meant he obliged a commitment to undergo physical checks at the Barmherzige Bruder hospital in Munich, arriving just after 09:00 local time, according to reports.
Newspaper Bild said Lewandowski arrived back in Germany from his holidays on Monday evening, before showing up to the hospital in a green Bentley.
He is said to have spent around an hour there, before departing. It remained to be seen whether, or when, Lewandowski would follow the hospital visit with a trip to Bayern's Sabener Strasse training ground.
Barcelona president Joan Laporta last week said his club had made an offer for Lewandowski and were awaiting a response.
German media reports said a further bid was expected this week, with Germany's Sky Sport saying a final offer of €50million, plus add-ons, was set to be submitted.
Lewandowski, who turns 34 in August, scored 50 goals in all competitions last season to lead all players across Europe's top five leagues.
Bundesliga champion Bayern has signed Sadio Mane from Liverpool since the end of last season, but they have also indicated they hope to keep Lewandowski.
If Lewandowski remains a Bayern player come the weekend, it could mean he faces an awkward appearance in front of the club's supporters.
Bayern will stage their team presentation event at the Allianz Arena on Saturday, which includes a welcome for new signings and an open training session for Julian Nagelsmann's squad.
That is followed by a pre-season trip to the United States for Bayern, who are due to play against DC United and Manchester City on that trip.
Lewandowski has entered the final year of his Bayern contract and would be able to leave on a free transfer at the end of that deal.