Youkilis has been on the DL since Aug. 18 with a lower-back strain and completed a two-game minor league rehab assignment with Triple-A Pawtucket on Wednesday. He went 2-for-8, hitting a home run in his final at-bat.
Youkilis participated in batting practice on Thursday and said he's feeling good and ready to go.
"As good as I can be for September," he said. "I'm good to go."
Youkilis is hitting .266 with 17 homers and 78 RBIs this season.
The news wasn't as good for right fielder J.D. Drew, who has missed the past six weeks with an impingement in his left shoulder. He was set to be activated from the disabled list Thursday, but the club will hold off because Drew suffered a sprained finger during his minor league rehab assignment.
During his second at-bat on Tuesday with Triple-A Pawtucket, Drew swung at a fastball middle-in and fouled it off. Somehow when he finished his swing, his bottom hand slipped off the bat and he got his finger up against the knob, bending the finger back.
"The diagnosis is he can play as tolerated," Red Sox manager Terry Francona said. "He's really sore, so we have to see where it goes. Whether it's a day, two days or a week, we don't know."
Drew was back with the team Thursday and was on the field for batting practice.
Drew said his shoulder felt strong during his rehab assignment.
"It felt really good. My shoulder, strength-wise, is really good," he said. "We've done a lot of work to get the strength back to where I wanted it. I was feeling really good there, having some nice rounds of batting practice, running well, felt good defensively."
Then the finger injury happened.
"It was just one of those fluke things that this pops up in that situation," he said. "I honestly didn't think it was going to be that bad. It hurt really bad when I did it, but I didn't think it was going to be that extensive of an injury until you wake up in the middle of the night and the thing is killing you. You realize something else is really going on.
"Unfortunately, it's my bottom hand. I think if it was my top hand it might be a little bit different. But the bottom hand is your power hand, the hand that has to stay on the bat. So we've got to make a determination. If I go up there and try to swing right now, as painful as it is and as loose as that ligament is, you jeopardize really tearing it. I think some healing time really is all it's going to take. As long as it heals and I'm pain-free."
Jackson seemed perfectly comfortable in his new environment Thursday afternoon in the home clubhouse at Fenway Park.
The Red Sox acquired the utility man from the Oakland Athletics in exchange for cash considerations and minor league pitcher Jason Rice late Wednesday night.
Jackson said he had no idea he would be traded and was informed only 15 minutes before the midnight deadline. He called the transaction a shock, but said he's thrilled to be in Boston.
"I'm excited," Jackson said. "I'm coming from a team that was 15 games out to a team that's in the middle of a pennant race. I'm in the AL East and probably one of the friendliest parks in the game."
He said he's comfortable playing any of the corner positions in the outfield and infield.
"Whatever they need," he said. "It'll probably be a bat off the bench and here and there playing against left-handers. I'll be prepared for whatever my role is."
Jackson, 29, is batting .249 with 17 doubles, one triple, four home runs and 38 RBIs in 102 games for Oakland this season. He played 50 games at first base, 28 in right field, 20 in left field and six at third base.
Doubront will work out of the bullpen for Boston after making 16 appearances as a starter for the PawSox in 2011 and posting a 2-5 record with a 4.22 ERA. He dealt with a few injuries this season and made two separate trips to the disabled list due to groin and hamstring injuries.
He recently was moved to the bullpen in Pawtucket and made two appearances, working a total of 3 1/3 innings and allowing only one run during that stretch.
"I feel great and my arm is great," he said. "Everything is fine now. I'm ready to go and help this team."
Joe McDonald covers the Red Sox for ESPNBoston.com.