Who should I start this week in fantasy football?

This week I'm faced with the daunting task of filling two RB spots with three extremely viable players. My first guy, Clinton Portis, is facing a stingy Pittsburgh Steelers defense that is superb at stopping the run, but Portis has seemingly been immune to tougher opponents throughout the year. And there's also the possibility of all his nagging injuries catching up to him this week. My second guy, Ronnie Brown, has dissappointed me for the past two weeks, but this week faces the 3rd worst rushing defense in the Denver Broncos, clearly a favorable matchup. Now option three makes this decision interesting. Earnest Graham hasn't been that impressive as of late either, whether it's because he's splitting carries with Warrick Dunn or being moved to fullback in light of the team's injuries. Despite this, the guy has talent, and he's on a formidable Tampa Bay team that takes on the worst rushing defense in the league this week when they travel to Kansas City. KC has been allowing an astonishing 196.6 rushing yards per game, allowing 5.6 yards per carry, and a total of 14 rushing touchdowns. Now clearly Portis and Brown are the two most talented out of the trio, but Graham's matchup is just way too good to ignore. It is a typical stud vs. matchup argument that we fantasy owners face week in and week out. But seeing as my team has fallen to 3-5, I'm on the brink of losing any and all playoff hope. So I'm asking you, my fellow fantasy football players, to help me in my time of need. Who do I start?