Per the Rangers beat guys on Twitter, Yu Darvish has been scratched from his scheduled start tonight. Derek Lowe will take his place instead.
All the people tweeting say that Darvish says he'd be starting if this were a regular season game, but with it being an exhibition, they are playing it safe.
On a separate note, there'd previously been discussion that Matt Harrison's schedule had him aligned to start on Opening Day, with Darvish's schedule setting him up to pitch Game 2. Depending on when Darvish makes his next start, that could change. And of course, no official announcement has been made about who will start Game 1.
This also potentially gives the Rangers the opportunity to see Derek Lowe throw multiple innings, and determine if he should be considered in the mix for the fifth starter job. The assumption has been that Lowe would be a long reliever, with either Robbie Ross or Nick Tepesch winning the fifth starter job, but if Lowe shows he's capable of pitching several innings, he could get consideration.