Dwight Powell got a good look at rookie Luka Doncic while both of them were in Las Vegas earlier this month for the summer league.Neither of them played in the games, of course. But Doncic, the No. 3 overall pick in the draft who the Mavericks clearly are expecting big things from, and Powell, the four-year veteran, did work out together in the desert."He's a great kid and you can tell he knows the game and can shoot," Powell said of Doncic.