Stefan Mattsson came out firing during Day 1 of the World Series of Poker's Main Event on Friday. In fact, the 28-year-old Swede was so aggressive that one of his tablemates -- three-time WSOP bracelet winner Barry Greenstein -- made it a point to ask who he was and where he came from about 40 minutes after the cards went in the air. "He was calling me the table captain," Mattsson recalls with a wide smile.