If Kevin Youkilis’ bothersome back does not allow him to play today against Blue Jays lefty J.A. Happ, there is a very good chance he lands on the disabled list. “It’s been a week now, so I think you look and see where he is [today] and then you make a decision what you are going to do and when you are going to get [him] back,” manager Joe Girardi said before last night’s injury-riddled 6-4 win. Youkilis came out of last Saturday’s game in Toronto because of lower back tightness and has not played since. Youkilis’ stint on the DL could be retroactive to Sunday. A player can’t be back-dated more than 10 days. Because David Adams and Gil Velazquez are candidates to be called up from Triple-A Scranton/Wilkes-Barre if Youkilis is put on the DL, the Yankees likely to try to avoid the move. Adams and Velazquez are not on the 40-man roster. Youkilis has not undergone tests to determine whether the problem is more than muscular. “They don’t think it’s an issue where we need a test,” Girardi said of the medical staff. “Let’s keep our fingers crossed for [today].” Youkilis, who said he landed on the DL last year with a similar problem because he didn’t give his back enough time to heal, said he hopes to avoid the DL. “If I’m ready to play in one to two days, I won’t have to go on the disabled list,’’ he said. “I’m not too concerned about it. Think I’ll be good. I made strides. Sometimes it’s just about doing less.I’m probably my own worst enemy a lot of times. I try to push it a little too much and next thing you know... it’s just a step back.“My [sacroiliac] joint locked up before, and now it’s loose and fine but there’s some soft tissue that’s tightened up and we’re slowly getting that out.’’ Last Saturday, Youkilis said he could play Sunday. He is in that mode again.