There was a young retriever about my size at dog park A. She's only a couple of inches taller than me. I had never seen her before. Everything was cool when we got there. I was playing mostly with an Aussie while Sienna restricted her adventure in the corner. There was a smaller dog and she attempted to play with him. She went back to the corner when 3 bigger dogs tried to greet her. After about 15 minutes, the younger retriever and I got into it. We barked and growled at one another and both of us were standing on our hind legs and 'boxing' with our paws. The retriever's owner was holding her collar but she got away. She did not even say any command to her dog. An older retriever and an English Setter came over and started barking at us. All of the sudden, I'm on the ground on my back and could not kick my way out of it. I yelped. My opponent was fierce and dominant. Her owner was finally able to control her while Mom clapped her hands and yelled my name. Mom was slow to react because she was closer to Sienna and she was a few feet away from me. I just stood there shaking things off. Two other owners came over and yelled "leave it" "down" to their dogs to no avail. Both dogs did not bother me. I think they knew who was the aggressor. After Mom took me to the side and gave me the once over, the bigger older retriever corrected the younger one and I heard her yelp. Sienna was safely at her corner minding her own business. After a few words with the owners and with the understanding that skirmishes will happen, we left the park to go to the smaller area. Better safe than sorry. Sienna and I continued playing as if nothing happened.