Baltimore ? Ray Lewis underwent surgery to have blood drained from his back Wednesday, which presumably will keep him out of Sunday’s game against the Atlanta Falcons.

Although the Baltimore Ravens have not ruled out the linebacker – they still list him as questionable – they don’t seem optimistic that he will be able to return in time to face the NFL’s top-ranked rushing attack.

“I don’t know how much of a difference it will make for this week,” coach Brian Billick said after Thursday’s practice.

With Lewis undergoing this procedure – some have related it to having a knee drained — it should increase his chances of playing next week.

“It’s my understanding that it will make a huge difference for him,” Billick said. “I think we’ve made real progress.”

If Lewis can’t play Sunday, Jarret Johnson is expected to make his first start at inside linebacker.

Lewis severely bruised his back Nov. 5 when safety Ed Reed accidentally hit him with his knee. Lewis missed Sunday’s 27-26 victory over the Tennessee Titans and has not practiced this week.

At his Monday news conference, Billick said Lewis had a “pool of blood” moving around his back that made him stiff and sore.

A two-time NFL Defensive Player of the Year, Lewis leads the Ravens with 97 tackles. With Lewis in the starting lineup, the Ravens haven’t allowed 100 yards to a running back in 12 home games.