Manager John Gibbons made the decision to start DeRosa as a way to get another right-handed bat into the lineup against Rays left-hander Matt Moore.
"DeRo had a good spring," Gibbons said. "He came in from the get-go, swinging the bat well. One thing about him, he's a steady defender as well. If he gets to it, you're out. And he gets you a good at-bat every time he's up there.
"He's on a nice little roll himself, so take advantage of those at-bats as well. Guys that hang around the game a long time because they know how to play, they know how to play in certain situations, they're not going to make mistakes. Their bodies slowed down, naturally, but you know what? You can count on him."
DeRosa entered Wednesday night with two homers and a total of four hits in his previous eight at-bats. One of those home runs came during a key pinch-hit situation on Monday night that helped sparked Toronto's come-from-behind victory after the club trailed by seven runs.
The 38-year-old DeRosa is hitting .220 (9-for-41) with three homers and 11 RBIs in 18 games.
Gregor Chisholm is a reporter for MLB.com. Read his blog, North of the Border, and follow him on Twitter @gregorMLB. This story was not subject to the approval of Major League Baseball or its clubs.