By Joe Brewin

Solidity at the back has been the main factor in securing top spot in Champions League Group F, according to goalkeeper Wojciech Szczesny.

Arsenal confirmed their place in the last 16 of the competition with a 2-1 victory over Borussia Dortmund on Wednesday with Robin van Persie’s brace proving decisive.

Arsène Wenger’s side have conceded just three goals in their five European group matches so far this campaign. Szczesny believes those mathematics have mattered.

“I think the defensive performances were key to winning this group,” he told Arsenal Player.  “It's just three goals [conceded] in five games against real top quality opponents, so I think that was it.

“Every single game we did a job professionally and we were very pleased with the performances.

“Defensively we did fantastically well. We seem to be playing with the same defence all the time now so we bond and understand each other. It seems to be getting better.

“Hopefully we can just keep on improving and get some more clean sheets. Hopefully against Fulham we'll get one.“

Shinji Kagawa’s last-gasp consolation ended Arsenal’s five-and-a-half hour run without conceding a Champions League goal.

Despite leaping to the praises of his sturdy backline, Szczesny admitted the late strike was something of a bugbear.

“I was a little bit annoyed as it would have been nice to keep three clean sheets in a row in the Champions League,” he said.

“But the most important thing is that we got the three points and we've qualified. I'm not going to complain too much about it.”

Copyright 2014 The Arsenal Football Club plc. Permission to use quotations from this article is granted subject to appropriate credit being given to www.arsenal.com as the source 24 Nov 2011