Baserunner/fielder confrontation

[Drizzle]

Hey all, I frequent the basketball boards and so I knew this would be a great place to ask this question. In a IM baseball game, the batter hits the ball right towards the foul line down the first base path, almost directly above the base. The fielder, seeing the eventual collision with the runner, tries to get out of the way and misses the ball. The ball lands JUST inside the line in fair territory. Who has to yield to whom in this situation, assuming the runner is staying in foul ground between the running lines? Thanks, everyone.