Reading manager Brian McDermott believes that his side's disappointing performance in the first half against Arsenal cost them the points.
The Royals suffered their sixth successive Premier League defeat on Monday when they went down 5-2 to the Gunners at home.
"In the first half they played very well and we didn't get close to them," he told Sky Sports News.
"We changed shape in the second half and got better, got two goals but the fifth killed the game. We could have got tighter in the first half.
"Their three midfield players were excellent, but the second-half response was good from our point of view. That game won't shape our season. We've got a lot of home games to come which will be defining for us."
The defeat leaves Reading at the foot of the table with nine points from 17 matches.
