We had a similar thing happen to us. We have two pitt bulls on the other side of the fence. Normally they are in a dog run and only seem to be out when the owners are home. They constatly bark at Vegas when we are outside playing and Vegas takes no notice of them. One day we were out and the dog was barking at the fence, I guess he had enough of Vegas running by the fence (which is an 8ft wood privacy fence) so the male Pitty decided he was going to jump the fence to get at Vegas. He got over and went for vegas. Vegas was fine with him untill the pitty grabbed him by his chops and started to shake and be nasty. Vegas got loose and is much more agile, he turned around and grabbed the pitty right back. The pitty was scared or shocked and started to run away from vegas, he tried to climb the 10ft chain link gate to get away. We yelled for the owners and he hopped the fence and grabbed his dog.
I was freaking out think that the pitt bull would do some damage because they have tons of muscle power in their bite. Vegas came out of it with a little cut, and the pit bull was fine. The owner felt really bad and offered to pay any vet bills. His dog was up to date on its shots so I wasn't to worried in the end.
I was very inpressed that Vegas was able to defend himself against a pitty and then scare him away. Needless to say the dog has not jumped the fence since. I am glad your babies had a much nicer greeting with the rotties.