Cat Chat scored a nose victory Wednesday in Belmont Park's opening day feature, the $150,000, Nassau County Stakes (gr. II) for 3-year-old fillies.Favored Xtra Heat, who had lost only one of 13 previous career starts, was runnerup with Shooting Party another 2 1/4 lengths behind. The loss ended a six-race win streak for Xtra Heat.Cat Chat, now undefeated in three career starts, carried 114 pounds, eight less than Xtra Heat, and covered seven furlongs in 1:23 to earn $90,000 for Jayeff B Stables. Bred in Kentucky by Herman Sarkowsky, the daughter of Storm Cat was purchased for $1.3 million at the 1999 Keeneland July selected yearling sale.The winner returned $9.70, $4.40 and $3.60. Xtra Heat paid $3.40 and $2.50 and Shooting Party was $3.50 to show.