Melbourne Victory have reportedly knocked back a second offer from German club Borussia Dortmund for young goalkeeper Mitch Langerak.

The Victory turned down a play for the 21-year old last month but kept the door ajar by telling Dortmund to come back with an improved offer.

The Bundesliga club have since done that and it is believed to have been a substantial improvement on the initial offer but once Melbourne have turned it down, shattering the promising shot-stopper.

"I'm very disappointed," Langerak said. "I had hopes that this offer [from Dortmund] would get accepted as it is a very substantial offer - one of the biggest ever for an Australian footballer - so for it to be turned down is very disappointing for me.

"I'm sure they [Victory] have got their reasons, but from my point of view it is a bitter pill to swallow. When one of the biggest clubs in Europe come knocking you have to think twice.

"I'm also disappointed that Victory didn't even bother negotiating. Dortmund stayed interested for four weeks while the Victory did nothing, which is very disrespectful.

"There was a deadline for Victory to respond to the offer, which they missed, and then just rejected it outright. I was sitting tight all this time not knowing what was going on.

"For any young player going overseas is something you dream of," added Langerak. "To get such an offer so early in my career is an honour and now it hasn't come off I'm disappointed.

"As a young player you don't know if you're going to get one of these opportunities ever again, especially at such a massive club [as Dortmund]. I'm sure the fans over here realise what a massive opportunity this is for me too."