An article in the Mid North Monitor, found here explains what can happen when these two species interact.
The Round Goby feasts on not only fish eggs and fish fry but mussels themselves. Not enough to control the spread of the mussels, but there is feeding happening for sure. The Gobies that feed on Zebra Mussels develop "Type E Botulism, caused by bacterial infection". As these contaminants make their way up the food chain from the Round Goby up, they can become toxic to walleye and other game fish, as well as birds of prey when they feed on the contaminated Gobies.
Give the article a read, there is more valuable information to be gleaned.