Joba Makes first start of career

• Blue Jays at Yankees, 7:05 p.m. ET: Joba Chamberlain (1-2, 2.28 ERA) makes his much-anticipated debut as a starter. Instead of having a nice, easy opponent, Chamberlain will go head-to-head with four-time all-star and Cy Young award winner Roy Halladay (6-5, 2.93 ERA). Halladay is 3-0 over his past four starts, and is coming off a pair of games in which he permitted just one run each time out.
• Mets at Giants, 10:15 p.m. ET: If not for Chamberlain, this would be the big news in New York. Pedro Martinez (0-0, 10.80 ERA), who has been out since April 1 with a strained left hamstring, makes his return. Adding to the intrigue, Martinez squares off against Barry Zito (1-8, 5.53 ERA), who has pieced together two respectable starts after opening the year 0-8.
• Tigers at A's, 10:10 p.m. ET: Jim Leyland made the decision to insert Dontrelle Willis (0-0, 7.50 ERA) back into the rotation in place of Armando Galarraga, who has been Detroit's most reliable starter so far this season. Dana Eveland (4-4, 3.66 ERA) followed up a great outing two starts ago with a messy 4 1/3-inning performance last time out.