J.A. Happ will take Josh Johnson's turn in the rotation on Thursday against the Red Sox, as expected.
Dealing with a triceps strain, Johnson missed a scheduled start in New York against the Yankees on the weekend. The injury requires rest. The right-hander was to play catch on Tuesday to test the arm before the Blue Jays determine when he'll next pitch. As is, they're looking at Friday or Saturday, against the Seattle Mariners.
Happ will face Dempster, of Gibsons, B.C., on Thursday. Dempster joined the Red Sox as a free agent in the off-season, and is 1-2 with a 3.30 ERA with a remarkable number of strikeouts, 43, in 30 innings pitched against 14 walks.
Happ is 2-1 with a 3.86 ERA in five starts, coming off a no-decision in New York where he drew a public admonishment for issuing a pair of walks in front of a three-run homer, after the Jays had taken a 3-0 lead on the Yankees.