Arsène Wenger's excitement at the onset of another Champions League group stage was undercut by exasperation, and it was not only directed at Uefa, the governing body, which has banned him from the touchline and dressing-room for the first three matches, beginning here against Montpellier on Tuesday night.

The Arsenal manager once again addressed the subject of Theo Walcott, who has been unable to agree to a new contract at the club and received a mixed reception upon his introduction at the Emirates Stadium on Saturday, during the 6-1 victory over his old side, Southampton. Walcott did not celebrate his late goal out of respect to them.

Wenger worried about the home crowd's reaction but, of greater intrigue, was his assertion that, with Walcott having entered the final season of his contract, there would come a point when the non-agreement between club and player represented a problem and influenced managerial thinking.

"It can," Wenger said, "but at the moment, I still hope to extend his contract so, at the moment, it doesn't affect me. Of course at some stage … if, in April, it's not done, you can think it will be difficult to do."

It is easy to feel that the point of friction has already arrived. In the final week of the summer transfer window, it was suggested to Walcott that if he did not sign the new deal on offer, which was worth £75,000-a-week, he would be sold. Manchester City were the most prominent among his suitors. Walcott has held out for £100,000-a-week.

Arsenal relented, Wenger saying Walcott would stay and stressing the club would continue to seek an agreement, even though there was a risk when the transfer window closed. Walcott could sign a pre-contract with an overseas club in January.

But Wenger has not named Walcott in his starting lineup since the club gave their ultimatum, albeit one that proved half-hearted. Walcott was used as a substitute at Stoke City and against Southampton, while in between times, he was left on the bench at Liverpool. Wenger said that he did not know whether Walcott would start against Montpellier.

Wenger was asked whether the groans that greeted Walcott on Saturday were a worry. "It is," he replied. "You want your players to be supported, no matter what kind of contractual situation they are in. I hope it will not affect him and that it will not affect our fans. Theo has gone through a lot at 23 years of age. A lot of positives, a lot of negatives and he's level-headed."

A key dynamic of Arsenal's encounter with Montpellier will be Wenger's inability to influence proceedings during the 90 minutes. He will not be permitted in the dressing-room beforehand or at half-time and he will be confined to a fidgety perch in the stands. The assistant manager, Steve Bould, will take charge, completing a meteoric rise. He was only promoted in the summer from his role as the under-18 academy coach.

It is Wenger's third suspension in a little over a year, after he served one match in last season's play-off first-leg against Udinese, which was a legacy of an outburst in the previous season's exit to Barcelona. He wrongly thought that he was allowed to communicate with his bench from the stands against Udinese and, after a failed appeal, he was given a further two-game ban. He incurred the current three for an outburst at the referee after last season's loss to Milan. The sentence took into account his recent previous.

"It [the ban] is a nightmare," Wenger said. "Honestly, many people in Uefa, even [Michel] Platini, said that we should still let people work, even if they are suspended. It's part of the job and therefore a restriction of work. But I don't make a fuss of it. They love to suspend me. How should they punish people? Financially? But they do both. They punish you financially and they ban you."

Wenger's continued to lament his punishment for communicating via his mobile phone with the bench against Udinese. "Honestly, nobody knows really, even at Uefa, what is allowed and not allowed," Wenger said. "Let's not forget that I was suspended last year for having done what they told me I can do.

"When I went back there and said: 'Why do you want to punish me?' They said: 'Because you communicated with your bench.' I said: 'But you allowed me to do it.' They said: 'We made a mistake. But we punish you anyway'."

Wenger refused to be drawn on whether he would start with Olivier Giroud, who left Montpellier for Arsenal in a £13m deal over the summer, although the expectation was that he would. Giroud won the French title and the golden boot at Montpellier last season. Wojciech Szczesny did not travel because of an ankle problem while Andrey Arshavin was simply overlooked from the 18-man party. Abou Diaby should return after a hip injury.

Montpellier have started the defence of their domestic championship sluggishly, with three defeats in five matches, but Wenger felt that they might have been distracted by their debut appearance in the Champions League. He remained wary of their threat. "Montpellier wait for this game and maybe they missed a bit their championship because there is so much attention on this game," he said. "What they did last season is a miracle because a few years ago, they were in the second division. For this club, it is something exceptional."