The Lightning will be without veteran defenseman Mattias Ohlund for up to a month, general manager Steve Yzerman said on Monday.

Ohlund, who was placed on injured reserve prior to the start of the season, will have arthroscopic surgery performed on both knees on Tuesday. The procedure will be performed by team orthopedic doctor Ira Guttentag.

The 35-year-old began to feel discomfort in his knees during the last week of preseason. Ohlund was kept off the ice beginning the morning of Sept. 29 prior to a preseason game in Montreal and the team had hoped rest would be enough to allow Ohlund to recover and get back on the ice.

But after undergoing MRI testing in Tampa early last week – which revealed no structural damage – Ohlund flew to Ohio late last week to get a second opinion from Dr. Anthony Miniaci at the Cleveland Clinic where it was confirmed that a procedure would help clean up some loose cartilage that is floating around.

“He felt that if he got it scoped out there, clean up some loose bodies – and it’s nothing major – floating around in there and that if he got it cleaned out while he is going to be off, because they have to been able to alleviate the discomfort that he’s been feeling,’’ Yzerman said. “He was showing a little bit of improvment, but he said it just didn’t feel right and figuring that if he was going to be out a little bit, let’s take that time and use it as wisely as possible, clean up whatever is in there irritating. So maybe he’s out a little bit longer, but when he comes he should feel better when he does come back.’’

Yzerman said the likely timetable for Ohlund’s recover could anywhere from a month to a month-and-a-half, depending on how the recovery process progresses.

“I’m going to say four to six weeks, but it really depends on how he feels, so it could be before that,’’ Yzerman said.

Ohlund missed time at the beginning of last season with similar discomfort in his knees.

With seven healthy defensemen on the roster and Tampa Bay carrying the maximum 23 players, Yzerman said he does not expect to be in the market to find somebody to fill in during Ohlund’s absence and head coach Guy Boucher will work with the current group while shuffling around the defensive pairings.

“It hurts because what it does is, we know have to put (Victor) Hedman against the top lines – and it’s not that he can’t do the job – but it asks a lot of other guys who are not in spots they are normally in,’’ Boucher said.