At first glance, you might think that China and Russia, as fellow revisionist, authoritarian states, present similar challenges to the Pax Americana. They don’t.
Russia has a GDP about the size of Australia’s. It is growing very slowly. It doesn’t sell anything anyone wants except oil and weapons. Its objectives are to dominate the near abroad by patching together something resembling the political structure of the USSR, and to regain the international clout the USSR enjoyed prior to 1989. As a result, Putin is basically just a spoiler outside of what he views as Russia’s natural sphere of influence; he makes life as difficult as possible for the US, not because it serves the economic interest of his people, but because it makes them feel strong and important.
China also seeks to dominate its near abroad, as it did for centuries. Its economy is growing by leaps and bounds. It pursues its interests predictably, and does not behave as a spoiler. Its objective is to become an equal partner with the US, preferably without any military confrontations. It has benefited from the current rules-based system, and does not wish to overthrow it, but it wants more say in how the system operates.
In the long run, dealing with Russian aspirations is a minor issue. Accommodating the Chinese in a manner that is mutually acceptable will be the greatest challenge of the 21st century.