Bayer Leverkusen's Swiss striker Eren Derdiyok has been ruled out for several weeks after stepping on a shard of glass in his bathroom.

• 0-0 draw against Bolton was 'not good enough'
• 'If you don't take your chances, it's going to be difficult'

Mikel Arteta has articulated the frustration in the Arsenal dressing room, describing the 0-0 draw at Bolton Wanderers on Wednesday as "not good enough" and warning that a top-four finish will be "tough" unless improvements are made.

Arsène Wenger made no significant signings before the closure of the January transfer window, which surprised and bewildered some of the squad's key players, who believed they needed the lift of a big-name permanent addition.

The group is now reconciled to closing ranks for a dog-fight over the next four months in an attempt to finish above Chelsea in fourth, which would see them qualify for the Champions League for the 15th season in succession. They trail Chelsea by five points and still have them to play at Emirates Stadium on 21 April. Newcastle United and Liverpool are also above them in the table and Arsenal play both these teams in March.

The stalemate at Bolton featured plenty of well-worn material, including profligacy, jangling nerves and post-match defiance from Wenger, as the manager maintained his belief that the team would finish in a Champions League place. But Arteta, who is not known as an outspoken player, pulled no punches in his assessment of the situation. The year has begun badly for Arsenal in the Premier League – their record reads: P4 D1 L3 – and the upturn needs to happen quickly.

"We should have won at Bolton, we had a lot of chances to win the game comfortably in the first half but once again we've not been good enough to take them," Arteta said. "And if you don't take your chances, it's always going to be difficult. It's not good enough. We have the players and the quality to have had a better result and we really need to start picking up points now.

"It's going to be tough to finish in the top four but I think we have the quality and the desire to do it. I know how good we are but we need to start showing it. We need to get on a good run and start winning games like we were doing a month ago because Chelsea are doing well."

Arsenal did win on Sunday in the FA Cup, coming back from 2-0 down to beat Aston Villa 3-2, but the over-riding emotion afterwards was of relief rather than any sense that a corner had been turned. They face Blackburn Rovers at home this weekend and there will inevitably be reminders of the 4-3 defeat at Ewood Park in September.

"We should win against Blackburn," Arteta said, reinforcing the game's importance. "We lost against them away from home and we should have won that one. We know they are going to make it tough as they are in a relegation battle and we know how hard teams in that situation battle."

The centre-half Per Mertesacker suggested Arsenal had been fortunate to go home from Bolton with a point, citing Wojciech Szczesny's save from Mark Davies as a crucial moment. But he also highlighted the imperative for the team as a collective to be better.

"I think we were lucky in the end," Mertesacker said. "We had to thank Szczesny in the changing room after the game for a great save. There's a lot of room for improvement.

"We have a very good side with lots of potential but we're not making the most of our opportunities and we need to improve on the pitch."

Jack Wilshere faces a scan in two weeks' time on his ankle, which will reveal the severity of the setback he has suffered in his fightback from the stress fracture that has wrecked his season.

The specialists say that the pain away from the "injury site" is a common problem for athletes who have spent considerable time in a medical boot and they are hopeful the midfielder can make a swift return to light training.

• Arsenal
• Bolton Wanderers
• Champions League

David Hytner
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