The Gerund phrase in this sentence Fighting is like champagne.
Explanation:
Gerund phrases are characterized by nouns acting like verbs ending wit an -ing effectively making it present participle or having the thing be happening in real time or being relayed in the real time to the reader or to the listener.
In this phrase the word fight is used as a noun but including the ing is also a verb, also the insistence on the comparison makes it in the present tense too as the comparison is being made in the present.
Thus it is the identifiable gerund phrase in the sentence.
