intoducing new puppy to aggressive neighbor dog

Question
Hi,
We bought a 3 month old male, neutered collie/golden(???) puppy from the Cleveland APL 2 weeks ago (Hermes).  I am trying to socialize him with as many other dogs as possible.  We have a 10 year old neutered Golden (Murphy) and they are getting along wonderfully.  I've also had my brother bring over his 2 dogs - a 6 month old yellow lab, and a 7 year old Golden (Jacob) and they all played together wonderfully.

My question is about our neighbor's 3 year old Golden,Boomer (yes - lots of Goldens!).  He's a very aggressive dog that never gets along with other dogs.  We have had him over to play since he was a puppy so he gets along with our Golden, but began to have some dominance issues with our other dog, who has since passed away, when he was about 18 months. He and my brother's Golden have never gotten along (we dog sit several times a year), they both act like they are going to rip through the fence and tear each others' throats out.

We brought Boomer over several days ago, I thought our yard would be best, and after running around and marking in several places he noticed the puppy.  He immediately bared his teeth and growled and began to lunge for him.  I removed him immediately before the puppy even knew what was going on, so no harm done, mentally or physically, to the puppy. Any ideas on how I can introduce these two in a safe manner, so there is not continuous animosity between the two.  I simply can not tolerate incessant barking and thrashing through the fence.

Unfortunately our neighbors have not trained their dog well, and he's out most of the day.  I can't go in our back yard without him barking constantly whenever he sees me and the dogs.  Clearly, with potty training, we are out quite a bit!  As the puppy gets older, I don't want the same reaction between Boomer and Hermes that happens with Jacob if they aren't properly acquainted. ANY insights and help will be greatly appreciated!  Thanks in advance,  Diane

Answer
Well the best way to fight dominance issues is to have the other dog come to your yard(not the other way around),but with a muzzle on(and on the others dogs as well)so he can sort out his role without anyone getting hurt-and that usually ends it

Now if that is not possible,the only other thing you will have to do is to build a wooden fence so that the dogs cannot see each other or get to each other