"For four innings last night, Jon Lester pitched like a man trying to make history as he held the Blue Jays without anything close to a hit. But he did not take the mound for the fifth inning, leaving with an injury that could change the course of the season for the Red Sox.

Lester has a strained lower left latissimus, a large muscle that runs beneath the shoulder. The lefthander does not believe the injury is serious but will undergo an extensive examination today.

The injury overshadowed an exciting 3-2 victory for the Red Sox, which ended with a play at the plate as Jason Varitek took a throw from left fielder Darnell McDonald and tagged out Edwin Encarnacion. The Sox have won five of their last six."