The Belgium international defender was frustrated by the loss at Old Trafford but expects Arsene Wenger's men to get back to winning ways after the international break
Thomas Vermaelen has rued Arsenal's "missed opportunity" in Sunday's 1-0 defeat to Manchester United, but has backed the Gunners to recover from the loss quickly.
The north London club had been unbeaten since losing to Aston Villa on the opening day of the season, moving to the summit of the Premier League, but fell to a first-half Robin van Persie header at Old Trafford.
Vermaelen admits the squad were disappointed with both their performance and their failure to move 11 points clear of the reigning champions, but is adamant that confidence is still high.
"We lost the game to a set-piece and that's a bit frustrating," the Belgian told the club's official website.
"Neither side really created too many chances. We didn't play well enough in possession of the ball to create any chances or score goals.
"We wanted to win the game and went to Old Trafford to do that. We were eight points ahead of United going into the match and had the chance to make it 11 points. It was a bit of a missed opportunity.
"But we're still top of the league and need to keep the confidence we've had over the last couple of weeks. There's no reason for that to change dramatically.
"We're still confident we can win games and we have a long way to go."
Vermaelen was a late replacement for Per Mertesacker, who was taken ill before the match, and insists he was fully fit and ready to make his first Premier League appearance of the season.
"It wasn't hard. I go into every game ready to play," the Belgian added. "I always make sure I'm mentally ready and physically ready, so for me it wasn't difficult.
"I knew it could happen at any moment so I'm always ready. I've been saying it for weeks and months and all of a sudden it happened.