Arsenal have made a strong start to their Champions League campaign but the club still have vexations and the unavailability of Abou Diaby is a particular cause of annoyance. The midfielder could take no part for France at Euro 2012 and his proneness to injury means that he must be handled with care. A thigh strain will stop him facing Olympiakos at the Emirates in the Champions League.

"It is really frustrating," said the Arsenal manager, Arsène Wenger, of the player's vulnerability and the taxing schedule for Diaby in World Cup qualifiers. "You think you are there but then it happens again. If France want him in Spain they should not take him for Finland and Belarus. The guy has been out for a year and then played four or five games. Give him a breather for two weeks to recover completely even if he is with the squad. It was a mistake to play him with the French national team."

The value of Diaby is all too fresh in Arsenal minds after the defeat by Chelsea at the Emirates. The player had to be substituted and the visitors capitalised. "When he moved out," said Wenger, "[Alex-Oxlade] Chamberlain takes his position and immediately we lost a goal. This was a ball that Diaby would have won easily. And he also gives us power in midfield."

That match, all the same, irked some Arsenal fans who saw harm done when Wenger chose to drop the centre-back Per Mertesacker from his line-up. The defender could well be reinstated against Olympiakos.

Arsenal are unlikely to be weighed down with worry about such topics given that they started their Champions League group by winning away in Montpellier.

On Wednesday night Wenger will serve the second part of the three-match ban imposed by Uefa after his criticism of the referee when Arsenal were trounced 4-0 by Milan at San Siro. Regardless of that, there have been indications of Arsenal regrouping even if Robin van Persie was sold to Manchester United. There is cause to think that the rebuilding should raise hope among the club's followers.

Patience, however, is a virtue Wenger is obliged to emphasise for the moment when Olivier Giroud, the £12m signing, is yet to score outside the League Cup, and has given few indications of the predatory quality he displayed with Montpellier. Wenger put no great stress on the striker doing damage against Olympiakos.

"Not only in the Champions League," the manager said of the contribution he anticipates from Giroud, "but I hope also in the future in the [Premier League] as well. You can say that he missed chances when he came on [against Chelsea] but he did have two. He is still in what I consider an adaptation period. It is a different team and different way of playing. The centre-backs really go for it here and he will adapt to that. Once the first goes in maybe the rest will happen as well."

Arsenal, however, have a perspective that takes in much more than the next entry on the fixture list. Michael Johnson, the American sprinter who won four Olympic gold medals, was at the club's training ground on Tuesday. Wenger did not succeed in playing down the significance.

"He has no role at the club," said the manager. "We sometimes send some players over to [Johnson's] school. If a player needs to work on something physical in the summer we send them there for preparation. It's a fantastic school but it's not directly involved with our team."

"We sent Ignasi Miquel [the 20-year-old Spanish defender] this summer and a few youth players. I personally sent Miquel. He is a tall boy and there is a deficit of muscle. I felt he was a boy who understands football but he needs to work on his power. I would have loaned him out this season to a Premier League club or even to a Spanish club to play. He is at an age now when he needs to gain confidence and [experience of] competition."

There was appreciation, too, of Carl Jenkinson's work at right-back as Bacary Sagna gets a little closer to recovering from a broken leg. For all the wounds, Arsenal may be getting a little closer to making this a healthy season.

Possible teams

Arsenal (4-2-3-1): Mannone; Jenkinson, Mertesacker, Koscielny, Gibbs; Coquelin, Ramsey; Oxlade-Chamberlain, Cazorla, Podolski; Giroud.

Olympiakos (4-2-3-1): Megyeri; Torossidis, Manolas, Contreras, Holebas; Modesto, Maniatis; Abdoun, Fuster, Machado; Djebbour.

Referee: S Moen (Norway)