Firstly, when you talk about Vishnu's incarnations (or Krishna's incarnations) you are talking about the same person. Krishna is nondifferent from Rama is nondifferent from Vishnu. The only difference is in Their pastimes.
Secondly:
"I will declare the mighty deeds of Vishnu, of him who measured out the earthly regions,
Who propped the highest place of congregation, thrice setting down his footstep, widely striding.
For this his mighty deed is Vishnu lauded, like some wild beast, dread, prowling, mountain-roaming;
He within whose three wide-extended paces all living creatures have their habitation.
Let the hymn lift itself as strength to Vishnu, the Bull far-striding, dwelling on the mountains,
Him who alone with triple step hath measured this common dwelling-place, long, far extended.
Him whose three places that are filled with sweetness, imperishable, joy as it may list them,
Who verily alone upholds the threefold, the earth, the heaven, and all living creatures.
May I attain to that his well-loved mansion where men devoted to the Gods are happy.
For there springs, close akin to the Wide-Strider, the well of meath in Vishnu's highest footstep.
Fain would we go unto your dwelling-places where there are many-horned and nimble oxen,
For mightily, there, shineth down upon us the widely-striding Bull's sublimest mansion."
--Rig Veda 1.154