The Polish striker underlined his already booming reputation as one of Europe's best strikers with an unprecedented four goals in Wednesday's semi-final first-leg win over Real Madrid.
A star performance has only fuelled speculation of Lewandowski moving to Bayern Munich or Manchester United, while he has also been linked with Juventus.
The 24-year-old's contract does not expire until the summer of 2014 and has no release clause but his representative, Maik Barthel, claims an agreement is in place.
Barthel is quoted as telling Sport Bild: "We are in agreement with a club and have the right to change this summer. All the claims of Dortmund are met."
After the famous win over Real, Dortmund had insisted they had not given up hope Lewandowski could remain at the club.
Dortmund coach Jurgen Klopp and chief executive officer Hans-Joachim Watzke both spoke of their desire to keep the 2010 signing from Lech Poznan.
But speculation in Germany is that Lewandowski will follow Mario Gotze in leaving Dortmund for bitter rivals Bayern this summer.