It's broke this morning that Chelsea have returned to the negotiating table for the England U21 winger after having an offer of €50m turned down on Club World Cup deadline day a fortnight ago.
The Blues are now offering closer to €60m and Freund says BVB must sell, knowing Gittens was upset seeing the original offer rejected.
He told Tribalfootball.com: "If the change doesn't come about, then it is wrong. Very clear, short answer. Because I think, because if you as a player think about changing - and I was even more extreme in our time, because there was no Bosman ruling- then you have to go.
"If you get to this point, I think it will be mentally difficult for him answer. And if Chelsea offers 50 (million euros) again, you may be more aware of how Chelsea see him.
"We are in agreement that they have the money. I think it would be better if there was a change."
Just like Ribery
Of the type of player Chelsea would be signing, Freund is convinced by Gittens' potential.
He continued: "Gittens has developed superbly. Everyone thought he could be a great outside striker. Now there was a little sporty depth. He of course has this signature move to the inside, like (Franck) Ribéry back then, coming to the inside on his right foot.
"As I said, I think that for him it would be an interesting change because he is an Englishman, he would like to play at the highest level in the Premier League."
- Steffen Freund was speaking to Tribalfootball on behalf of Hochgepokert.com