Arsenal were comfortably second best at Preston North End in the first half - and Olivier Giroud was shocked by the hosts' intensity.
Olivier Giroud and Aaron Ramsey conceded Arsenal were taken aback by Preston North End's desire and intensity in the first half of their FA Cup third-round meeting at Deepdale on Saturday.
The Gunners started woefully and found themselves 1-0 down inside seven minutes thanks to Callum Robinson, who could have had a second midway through the half.
Jordan Hugill and Paul Gallagher also missed excellent chances for North End in the opening 45 minutes before Arsenal improved markedly after the interval.
Ramsey levelled matters within 60 seconds of the restart and Giroud netted the winner a minute from time for his 10th goal in his last eight starts for the club.
"We wanted to start the game better than the last game at Bournemouth [when Arsenal came from 3-0 down to earn a draw on Tuesday], they surprised us with their commitment," Giroud told BT Sport.
"We were not in the game in the first half and we obviously wanted to be in the second half and show some character.
"We've done it with the early goal and we pushed and pushed to the end so one more time we've shown strong team character but we want to start better in games.
"Surprised yes, they put a lot of intensity into the duels and all the team was beaten so we wanted to show something else in the second half.
"We've done it, but we need to start better, but we are pleased with the amazing support of the fans to win this game."
Ramsey's goal - a fine effort from the edge of the box - was his first of the season and he echoed the sentiments of his team-mate in expressing surprise at Preston's performance.
"I've played in the Championship [for Cardiff City] and I know how difficult every game is. They took us by surprise with their commitment and we didn't match that," he said.
"Second half we needed to have a different attitude and I think we showed that. It's nice to score finally and that gave us a bit of momentum to go forward and win the game.
"Finally one's gone in so hopefully a few more will follow but I'm just happy we won the game."