Doubt about using plural form in this phrase "discuss about ...."
Politics isn't really the plural of "politic" (which is an adjective). As a topic, "politics" is singular; as shorthand for "political considerations", it's plural, but again, one political consideration isn't "a politic", it's still "politics".
Sports is a little different. "Sport" is commonly used in British English, but not as common in American English. In both, "sports" is commonly plural. But it can still be used as a mass/uncountable noun.
Here's a good answer for sport.
Here's a good discussion for politics.