Manchester United's Wayne Rooney has labelled last season's seventh-place finish a "disaster" - but says new boss Louis van Gaal will set things right.
"This is a really bad result for us. But we will learn, especially with the manager we have got," said Rooney, 28.
"Maybe after a good pre-season we were over confident," added the captain.
|Van Gaal's pre-season record|
|WIN 7-0 v LA Galaxy|
|WIN 3-2 AS Roma|
|DRAW 0-0 Inter Milan (United win 5-3 on penalties)|
|WIN 3-1 Real Madrid|
|WIN 3-1 Liverpool|
|WIN 2-1 Valencia|
The 2012-13 champions, who sacked David Moyes in April after just 10 months in charge, headed into this campaign with high hopes.
Last season saw United finish their lowest in Premier League history, and they failed to qualify for European competition for the first time since 1990.
Rooney, who scored against Swansea, said: "We know last season was a disaster. It wasn't good enough and we were ready for the start of this season.
"But we just have to look at the bad points and cut them out. If we do that we will win games."
However, Red Devils midfielder Darren Fletcher, 30, thinks the team will respond quickly to their first opening-day defeat since 1972.
"I believe we're going to have a very good season," the Scot said. "All the players believe that too."
"This whole club is about bouncing back from adversity."
United have lost experienced heads like Ryan Giggs, Rio Ferdinand, Nemanja Vidic and Patrice Evra from the playing squad and are yet to sign replacements.
Van Gaal's team selection against Swansea featured debutants Tyler Blackett, 20, and midfielder Jesse Lingard, 21, but Fletcher has backed the youngsters to come good.
He said: "People talk about the players that have left but I see it in the eyes of the young players, they're ready for it and determined to show people how good they are and we're determined to show people how good the team are.
"You have to be a big character to play for this club."
United's next Premier League game is away at Sunderland on 24 August.