Arsenal manager Arsene Wenger remains confident his men can finish the job and qualify for the Champions League after battling to a goalless draw against Besiktas in Istanbul, where midfielder Aaron Ramsey was sent off.
The Gunners were stretched by Slaven Bilic's well-drilled outfit in the first leg of their play-off at the Ataturk Olympic Stadium, where the hosts almost took the lead right from kick-off through a long-range effort by former Chelsea striker Demba Ba which hit the crossbar.
However, crucially Arsenal held out and but for some poor finishing by Olivier Giroud could have netted a crucial away goal themselves, with substitute Alex Oxlade-Chamberlain seeing his shot touched onto the post in the closing stages.
Ramsey - who scored a stoppage-time winner against Crystal Palace on the opening day of the new Barclays Premier League season - was dismissed for a second yellow card with 10 minutes left when he was ruled to have pulled back former Arsenal midfielder Oguzhan Ozyakup.
Arsenal, though, will welcome back German World Cup winning trio Mesut Ozil, Per Mertesacker and Lukas Podolski ahead of next week's second leg at the Emirates Stadium, when they will be out to secure a 17th successive campaign in the lucrative group stages of Europe's elite club competition.
"We always want to win, but Besiktas could have won the game, and we could have won the game as well. Maybe a draw is a fair result because both teams had chances to win," said Wenger, who confirmed he reported to UEFA than an object had been thrown at him as he left the pitch at full-time.
"We know the second leg will be certainly tight again, but we play at home, so the task is clear for us - we want to win."
Arsenal player ratings vs Besiktas
Arsenal player ratings vs Besiktas
1/12 Wojciech Szczesny
Nearly caught out after just five seconds by Demba Ba's stunning kick-off effort, but made a couple of fine saves as the game progressed. 6/10
2/12 Mathieu Debuchy
A less attacking shift than usual. 5
3/12 Calum Chambers
For the majority kept to his task diligently alongside Koscielny. 6
4/12 Laurent Koscielny
Given a torrid time by Demba Ba in the first half but settled into the game more in the second. Handed the captain's armband after Arteta went off. 6
5/12 Nacho Monreal
A solid, if unspectacular performance. 6
6/12 Jack Wilshere
Grew in dominance as the game wore on. 7
7/12 Mikel Arteta
Night ended after ankle injury from clash with Demba Ba. 5
8/12 Santi Cazorla
Tricky run nearly warranted a goal but sliced his effort wide. 6
9/12 Alexis Sanchez
A menace that Besiktas could contain but not fully clicking with team-mates yet. 7
10/12 Aaron Ramsey
His delightful pass deserved a goal from Giroud. Two bookable offences saw his night end after 80 minutes. 6
11/12 Olivier Giroud
Touch eluded him when he needed it most in front of goal. 5
12/12 Best of the bench: ALex Oxlade-Chamberlain
Mesmerising run into the box deserved a goal, but shot tipped onto the post. 6
Despite leaving Istanbul with a positive result, Wenger was less than impressed by the overall performance of Serbian referee Milorad Mazic, who sent Besiktas boss Bilic to the stands just before full-time.
The Arsenal boss added: "Neither the first nor the second yellow card was deserved for Aaron Ramsey. When you see some of the fouls that have been made tonight and we go home with Ramsey (given) a red card, it is a bit unbelievable.
"In the second half the performance of the referee was very bad.
"Ramsey's second yellow card, I cannot see where that comes from, it was a huge decision.
"I felt just a lot was wrong in the second half but, overall, it was a difficult game maybe to referee as well because everybody did fight for every ball, so maybe it was not easy for the referee as well."
Nevertheless, Wenger was happy enough to have seen his side leave undefeated, if counting the loss of captain Mikel Arteta to an ankle injury.
"Besiktas played with 100 per cent pace in the game and did fight for every single ball, and it was quick. We needed a great level of concentration," he said.
Arsenal have been linked with a £15million move for Olympiacos defender Kostas Manolas, to cover the departure of captain Thomas Vermaelen. Wenger, though, insisted the club "are not close to signing anybody".
Bilic, meanwhile, hopes he will be able to lead his side at the Emirates Stadium, having apologised for his indiscretion.
The Croatian former West Ham and Everton defender said: "If that was a reason, many coaches would be missing from the dug-out.
"I have apologised. I made a mistake. Maybe I overreacted in that situation when he stopped the game we were in a good position, two against one."
Bilic believes his men can lift themselves for a big performance next week.
"We are going to London not to go shopping in Harrods, but to try to fulfil some would say our dream, I would say our task, our plan," he said.
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