mat uuniiw

Lit. "they play against each other" or "he plays against himself".

Mat "himself, each other"

Uuniiw (ucheniw) "is opposed, against, opposite to; challenges, competes, plays together with someone"

Defined as "gambles, plays against" in Mesa Grande dictionary. Barona dictionary defines as, "they play as a team".

For "gambles", other speakers such as from Barona tend to use suunaar/suunaarr (suunarch/suunarrch) "he plays (child), plays competitively, gambles, plays cards" (Mesa Grande suunaarr "plays alone")