At 7.5 games up, the Red Sox have certainly put the burden on the Rays: sweep, or be left in an almost hopeless situation. Even in 2011, about as awful a collapse as you can imagine, the Rays were within four games of the Red Sox with 148 games played, and the Sox still had to finish 4-8 for the Rays to pip them in the standings.
Anything short of a sweep, and the Red Sox are at least 6.5 games up. Even playing .300 ball from thereon in would force the Rays to go on an impressive tear to end the year.
And a series win for the Red Sox? That would end it, if not mathematically, then at least within reason.
It's not going to be easy to start off on the right foot with David Price on the mound, even if Clay Buchholz is 90% back. But there's no such thing as an unwinnable game, and this one doesn't even come close.