Identify the part of speech of the word in bold. During the first quarter of the game, their center played well against our forwards.

The part of the speech is : Adverb.

Explanation:

An adverb is a word or an expression that is used in English Grammar that modifies a verb, an adjective, a determiner, a clause, a sentence or a preposition also.

It adds a quality to all these expressing their relation with time, place, circumstance, cause, degree or the manner. They are intensifiers and they even come in the form of an adverb phrase.