Dec 11 (Reuters) - Arsenal were caught between two stools against Napoli on Wednesday, manager Arsene Wenger admitted after his side staggered into the last 16 after a 2-0 defeat in Italy.
Arsenal needed to avoid a heavy loss to qualify but Wenger suggested they were unsure of whether to sit back or try to grab a goal.
"The most difficult is when you are in between - do we attack or defend?" Wenger told reporters.
"As long as we didn't score, they had hope. Maybe what helped was that Dortmund were drawing 1-1 and maybe they put the handbrake on, that's why we didn't get too much pressure in the end."
Napoli were heading for the knockout stages when they led 1-0 and Dortmund were drawing 1-1 with Olympique Marseille. But a late Dortmund goal led to Napoli's elimination even though Rafael Benitez's side scored a second goal in injury time.
"We are happy to be through because it was very difficult," Wenger added. "We took it very seriously but in the second half we dropped physically a lot, we had a game on Sunday.
"Naples played very well tonight but we were a little bit on edge for some minutes. It was nervous in the end, but we got through."
Arsenal, the Premier League leaders, now have a quick turnround because they travel to Manchester City for a top-of-the-table clash at midday on Saturday.
Wenger disagreed with the sending-off of midfielder Mikel Arteta in the second half.
"He's absolutely convinced that he didn't make a foul and it was very harsh but he already had a yellow card," he said. "I felt it was a very harsh second yellow card." (Reporting By Brian Homewood; editing by Robert Woodward)