Kyrie Irving returned to the lineup and scored 25 points while wearing a mask, and the Boston Celtics beat the Brooklyn Nets 109-102 on Tuesday night for their 13th straight victory. The Celtics remained unbeaten since an 0-2 start heading into their showdown Thursday in Boston against the NBA champion Golden State Warriors. Marcus Morris added 21 points and 10 rebounds, and Jayson Tatum scored 19 points for the Celtics.