Arsenal have been given a major boost after Sol Campbell pronounced himself fully fit, but the Gunners are waiting to hear the extent of Gilberto Silva's back injury.
The Brazilian midfielder, who is seeing a specialist, missed Arsenal's 1-0 win at Manchester City on Saturday and could be out for at least a month. That would be the case if the problem is an old one that has become inflamed, however, it could turn out to be something more serious.
Gilberto Silva first felt the injury during the 4-1 win at Everton in the opening game of the season and he now fears he could be ruled out of the entire group stage of Arsenal's Champions' League campaign as well as crucial League games against Manchester United, Tottenham and Chelsea.
However, as Arsenal prepare to face Rosenborg in Norway tomorrow night, there is more encouraging news from England centre-back Campbell. He has told his manager Arsène Wenger that he is ready to play in Norway.
Campbell, who played his first senior game of the season against City after recovering from injury, said yesterday: "I will be able to play three games a week, no problem. The fitness is there and I feel good and sharp. If the manager wants me to play on Wednesday then I would be able to do so."
Campbell's return to fitness is also good news for the England coach, Sven Goran Eriksson, prior to the World Cup qualifiers against Wales and Azerbaijan next month.
"This is an important time for the England team and I would love to be involved," Campbell said. "There are several players in the squad at their peak and now we want to push on past that quarter-final stage. What we are missing is that vital bit of luck, that rub of the green. If we get that, then we can make that step, I am sure.
"It was important that I had that break to make sure the Achilles injury healed. If I had played with it then it would have just been there all the time and not got better. I did a mini pre-season when I started training again and I put in a lot of hard work. It was a frustrating time with the occasional twinge and so on but I am through that now."
Arsenal's midfielder Robert Pires should also be fit after missing out against City because of a foot injury.
Thierry Henry, meanwhile, has warned his Arsenal team-mates to take the threat of Rosenborg seriously. The Norwegian champions lost their first group game to Panathinaikos in a fixture that Henry believes they should have won comfortably. "It will be hard to beat them," he said. "I was surprised how well they played. They were new to me. I'm a bit apprehensive of what they can do. We will have to be careful."
He added: "They will obviously be up for the game. They are a handful of games away from retaining their title, so they are well into their season and will be near top form."
Elsewhere in the Champions' League, the Milan vice-president, Adriano Galliani, has assured supporters of the Italian side that there will be no further slip-ups against Celtic tomorrow.
The Rossoneri have taken just one point in Serie A from two games in the San Siro this season. A 2-2 draw with newly-promoted Livorno was followed by a surprise defeat by another promoted team, Messina, in midweek. They did, however, beat Lazio 2-1 away on Sunday.
Galliani said: "I spoke with Paolo Maldini and asked him why there was only one point with both Livorno and Messina at home, and six points away from the San Siro. He answered that they didn't know the opponents, as they were both newly-promoted. I told him that Celtic and Reggina [Milan's next Champions' League opponents] are not newly-promoted. So the fans don't have to worry."
Galliani believes the presence of the in-form striker Andrei Shevchenko can influence the game. Shevchenko scored twice in five minutes in Rome on Sunday and is close to overtaking Marco van Basten's record of 124 goals for the club.
"Van Basten is a legend for me," Galliani said. "After him, Milan did well to sign George Weah, a great star, although he didn't score too much. And then they have found Shevchenko."