Arsenal's home defeat by Eintracht Frankfurt showed manager Unai Emery "may have taken the team as far as he can", said ex-Gunner Martin Keown.

Arsenal took the lead through Pierre-Emerick Aubameyang but Daichi Kamada's double secured a 2-1 victory for Frankfurt, although the Gunners remain top of Europa League Group F.

Keown said his old club's second-half performance was a "shambles".

"He seems to have lost the players and the desire has ebbed away," he added.

The Gunners will seal qualification for the knockout stages if they avoid a heavy defeat at Standard Liege in their final group game, but Keown questioned whether Emery can still "motivate" his players.

The final whistle brought boos and jeers from fans at a sparsely-populated Emirates Stadium and means Arsenal are on their longest winless run since February 1992.

Disgruntled Arsenal fans held up banners at the Emirates Stadium, calling for Unai Emery's departure

"The team selection, the team motivation, the substitutions, the performance, everything was missing here. It was a dreadful performance," Keown told BT Sport.

"I think maybe the manager may be in a position where he feels he needs to step aside now. Serious questions need to be asked. This is as bad as I have seen it and it is relegation form [when they return to Premier League action].

"Decisions need to be made, otherwise the club is going to plunge further down the table.

"The fans turned on [former manager] Terry Neil, 37 years ago. I was at the club when it happened and things got very toxic. I think we are getting close to that again."

But former England defender Keown added: "I think he will get the time because there isn't a ready-made replacement."

'I am being positive but I'm also realistic'

Emery, who has won the competition three times as a manager and also steered the Gunners to the final last season, said his side "lost control for 15 minutes".

"We showed an improvement in the first half and we had a lot of opportunities to score but we did not take them," said the Spaniard, whose side have gone seven games without a win.

"The first five or 10 minutes of the second half were good but then we lost control and we could not change the result. We tried to come back but we did not create any big opportunities to score.

"I am being positive but I'm also realistic and we lost against a good opponent. We have improved from our last match and we are still first [in the group] and have the opportunity to qualify, but we missed the opportunity tonight."

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Following Emery's comments, former Arsenal striker John Hartson said the Spaniard's interview "sounded a bit delusional".

"It's like he's hiding from the reality that his team just aren't good enough," said the Welshman.

"I'd love a manager who was as kind as that. I know he's trying to protect his players and if I performed like that I wouldn't want to go into training and see my manager."