Manchester United have injury concerns over Patrice Evra and Ryan Giggs ahead of the Champions League game at CSKA Moscow on Wednesday.
Sir Alex Ferguson is hoping that Serbian defender Nemanja Vidic, who missed Saturday's 2-1 Premier League win over Bolton Wanderers in Manchester at Old Trafford with an ankle injury, will be fit enough to return in mid-week.
But he admits he has concerns over both Evra and Giggs after they sustained knocks against Bolton.
It was not a convincing performance from United but they returned to the top of the table thanks to Chelsea's loss to Aston Villa.
And although Ferguson is calling for improvements at the back - his defence have kept just three clean sheets in nine Premier League matches - he was happy to move back to the top of the table despite suffering further injuries.
United's defence was the key to last season's title win and although Ferguson reckons the league is tougher this season, he believes his players can do better.
"Giggs is doubtful for Moscow with a knock," said Ferguson as he surveyed his casualty list.
"Evra we will look at tomorrow (Sunday) and he may be doubtful. Vidic should be okay and definitely will be fit for Liverpool (a week on Sunday).
"I think (Dimitar) Berbatov will be okay and we will try and get Wayne Rooney ready but he will be okay for Liverpool."
Ferguson added: "In the past few years we have had runs of games when we haven't lost goals and that's been important in winning the championship and we have to get back to that.
"We were in a comfort zone at 2-0 and maybe we were relaxed in terms of our play and we should have finished the game off but we didn't.
"Sometimes you can leave yourself regretting that but we got through and with the other results it's been a good day for us.
"All the top teams have to accept it's a tough league."
Veteran Dutch goalkeeper Edwin van der Sar played for the first time since suffering a hand injury in pre-season and Ferguson feels that the former Ajax player will make a big difference to his defence.
"Edwin was fantastic. He has the composure and the experience and steadiness at the back that's what his career is about."
United overcame Bolton thanks to an early Zat Knight own goal and Antonio Valencia's stunning finish.
But Matt Taylor's late goal set up a tense finale at Old Trafford.
Bolton manager Gary Megson felt his side could have been even better if they had started at a decent tempo.
However, he admitted the international break had a considerable effect on players like South Korea's Lee Chung-Yong and Israel's Tamir Cohen.
"These international breaks for small clubs like ourselves are a disaster," Megson said.
"Tamir Cohen looked nothing like the player he was before he went away and Chung-Yong looked a shadow of himself. Next time we will have to look at changing the team regardless of form."
Megson also feels his side, who went into the United game on the back of a five-match unbeaten run, are moving in the right direction and shedding their old reputation for being direct and negative.
He added: "It makes us smirk a little bit because managers talk about set pieces and things like that and we've been bitterly disappointed in our defending of set pieces.
"Other managers have called us a big, physical team but in that you've got Lee Chung-Yong, Matt Taylor, Ricardo Gardner. We're not that kind of team anymore."