I think Matsui is more injured than he is letting on and needs to be benched. I’d use Jason Giambi as the DH and stick with Doug Mientkiewicz at first. Giambi’s glove should be hidden so he can’t play first.
As for Melky, he’s a kid and kids are inconsistent. He’s liable to go 3 for 4 and throw two guys out at the plate. At least he’s had a few RBI lately.