Skipper Scott Brown and defender Mikael Lustig will be missing again for Celtic's SPL clash against Motherwell at Fir Park on Wednesday night.
Brown has seen a specialist about his abductor problem and will discover on Monday if he requires surgery while Lustig is out with a thigh injury.
Defender Charlie Mulgrew is a doubt with a glute problem.
Motherwell will be without defender Fraser Kerr after he missed the weekend defeat to Ross County through illness and remains out of action.
Fellow defender Zaine Francis-Angol is a doubt after being forced out of Saturday's match.
Midfielder Tom Hateley and defender Steven Hammell both missed the clash with the Highlanders and McCall hopes one of them could be passed fit for the visit of the Hoops.
The Teessiders face Rafael Benitez's men in their delayed fifth-round tie at the Riverside on Wednesday evening hoping to claim another Barclays Premier League scalp after dumping neighbours Sunderland out of the fourth round of the Capital One Cup.
However, Mowbray is acutely aware of the threat posed by the Blues even if Benitez chooses to shuffle his pack, and has told his side only hard graft will give them a chance of containing them.
He said: "When you haven't got world-class players, you have to first and foremost have a work ethic. You have to try to condense space, you have to try not to be isolated one-on-one in certain areas of the pitch.
"And yet, you have to balance that off with having an attacking threat. You have to have a way of trying to score a goal and if you have everybody back, it's very unlikely you are going to have too many attempts. That's the balance for any manager.
"Watching Manchester City at the weekend, it was 'You have an attack, we have an attack and see how can hurt the opposition the most'.
"I would have to say, we won't be playing like that because I doubt we are going to leave three up front and wait for our defence to give it back to them and we attack them and they all run back.
"That's the difference. Athletically, we have to cover more ground than they do. They can rely more on their technique and their talent to pick the right pass."
Boro will head into the game having won only one of their last nine npower Championship fixtures, a run which has seen them slip out of the play-off places.
But it is Mowbray's opposite number Benitez who will head into the contest knowing failure will pile the pressure on to him with his detractors becoming increasingly vociferous.
However, the Boro manager is wary of the strength which can emerge from adversity and believes the Spaniard's track record proves he can handle the heat.
He said: "In adversity, the group of players should be feeding off that and becoming stronger and more unified, and I am sure that's happening at that club.
"The decision for Rafa to take that job was made because he is a top manager who has won European trophies, who has won leagues in just about every country he has been to.
"He is a good football man. I don't know him well, but I have been in his company and he loves to talk football tactics.
"I have only got respect for Rafa Benitez. It is a tough job, of course, but he seems very professional, long in the tooth regarding his job from the point of view of getting on with his job and trying to win trophies for the club.
"Every football manager at times feels the wrath of the support and you have to be very, very single-minded to sit in a football manager's job in 2013 because of the social media aspect of the world now, everybody can do your job, everybody has got an opinion.
"You have to be single-minded and I think Rafa is showing everybody he is pretty single-minded, getting on with his job, trying to win games."
The south Wales outfit have seen days like this before, notably following their promotion to the Premier League in May 2011, but the added edge of securing a first piece of major silverware in the club's centenary season ensured a massive presence along the 1.2-mile route.
Even the cold and overcast weather conditions could not put a dampener on the occasion as fans crammed along the city's streets to acclaim the players, management and staff.
The open-top bus carrying the players set off from the Dragon Hotel before making its way down the city's Kingsway and heading down to St Helen's Road to the Guildhall for a civic reception.
It seemed apt that part of the route took the current squad within sight of where the Swans' former Vetch Field home once stood, for it was almost 10 years ago at that very venue that this fairytale story began.
A 4-2 victory over Hull, courtesy of a hat-trick from striker James Thomas, now an ambulance driver, ensured Swansea retained their Football League status.
Current squad member Leon Britton was the sole survivor from the side who beat the drop to feature at Wembley.
Club captain Garry Monk, who stood at the front of the bus holding aloft the trophy with vice captain Ashley Williams, is another who can recall the club's days in the fourth tier.
Back then, manager Brian Flynn would hold training at any available space: a local astroturf, a free playing field, or even on the beach.
There are question marks over how long the likes of Laudrup and inspirational top scorer Michu may remain with Swansea, but there were few among the cheering throngs who were too concerned by such thoughts.
Instead they will dream of forays into Europe as part of the Europa League spot secured by Wembley glory, and wonder what will happen in the next chapter of this most remarkable of sporting stories.
The Tangerines head north knowing a win would take them to within just a point of Terry Butcher's Caley Thistle in their quest to climb the table as they look to finish the season with a flurry.
McNamara watched his side concede two goals in last Sunday's 2-2 SPL draw with Hibernian at Tannadice, a game in which United required a late penalty from Johnny Russell to earn a share of the spoils.
And McNamara does not want to see a repeat of any slack defending when they head to the Highlands for their important SPL clash.
McNamara said: "Hopefully we have learned our lesson from that point of view.
"It's something we have to work on and have got to do better.
"Inverness have been playing well this season and thoroughly deserve to be where they are in the league, which is second top.
"They score a lot of goals so obviously we want to keep things tight at the back and not help them in any way.
"We were annoyed at the goals which we lost against Hibs but that's in the past and we have to try and improve on that."
McNamara takes his side to the Highlands to face Euro-chasing Inverness and knows they will have to be firing on all cylinders if they are to return to Tayside with all three points.
He said: "We know it will be nothing other than a difficult game.
"It will be a test for the lads and we have to start the game better than we did against Hibs when we were slow to get going.
"Having watched Inverness, it's clear they have had good legs and can get about the park so they are dangerous opponents.
"But we have to focus on our own strengths and hopefully take the game to them.
"The league is so tight that a few wins can make a big difference which is what we're aiming for."
United have signed Swedish defender Marcus Tornstrand but the 23-year-old free agent will not feature at Inverness as he works to build up his match fitness.
Gavin Gunning is sidelined following a knee operation but McNamara has no fresh injury worries.
