The 6-foot, 198-pound cornerback also would play out of his natural position.
Phillips didn't practice Friday after receiving limited work the previous two days because of a sprained medial collateral ligament in his left knee. The injury occurred late in Sunday night's game against the Chicago Bears, and the Giants said it is unrelated to the microfracture surgery that ended Phillips' 2009 season after just two games.
"I guess (a game-time decision) is where it's heading right now," said Phillips, who was listed as questionable on the Giants' injury report for this Sunday's game. "We will see."
Phillips called it a "minor" sprain, and early in the week, the Giants had simply said the knee was tired and sore. Though Phillips' practice limitations appeared precautionary at first, the situation appears to have worsened.
The injury news wasn't all bad. Running back Ahmad Bradshaw received limited work in Friday's practice after missing two days with a sprained right ankle, and he said he should be ready to go.
"I didn't have any setbacks at all," he said. "It's just something that happened. I've had ankle sprains before. It's just something that occurs. There's no doubt I'll play."
"It's something new for me, so I just have to go out and try to make some plays," said Jackson, who only took his first career practice snaps at safety this week. "It's not that different because in college, you can end up playing half (the field) at corner. It's pretty much the same.
"In college, I played the boundary corner, so I was a run-support corner. It's more read and reaction than straight man-to-man. I guess they feel like they have a playmaker in me, so I'm excited."
Copyright 2010 by The Associated Press