(Portland, OR)  --  The Portland Trail Blazers will try to avoid elimination from the NBA Playoffs tonight when they host the San Antonio Spurs in Game Four of their Western Conference semifinal series.  The Blazers are running a three-games-to-none deficit after losing Saturday, 118-103.  Mo Williams missed Game Three with a groin injury and isn't expected to play tonight.  Tip-off at the Moda Center is scheduled for 7:30.