Michael Carrick admitted Manchester United have "a lot to learn" after suffering a surprise 2-0 defeat at Hull in their opening game of the Premier League season on Saturday.
Carrick's side were ripped to shreds by the rampant Tigers as first-half goals from Semi Ajayi and Nobel Mendy caused a shock at the MKM Stadium.
United were toothless in attack and inept at the back, a fatal combination that allowed promoted Hull to celebrate their return to the Premier League after a nine-year absence.
Hoping to challenge for the title after finishing third last season, United looked well short of the standard set by champions Arsenal.
Carrick conceded United have much to work on after being punished for sloppy defending at two set-pieces.
"We have a bit to improve on, it was never going to be perfect. Going behind makes it more difficult, against a promoted team at home," he said.
"We can't give them much and they had opportunities. We're disappointed but it won't knock us."
Carrick had warned against underestimating Hull and next week's opponents Ipswich, the second promoted side United will face this season.
His caution proved well founded, but Carrick vowed United would be better for the painful defeat.
"It's for us to know and to improve during the week and keep getting stronger as a group. We have a lot to learn from it," he said.
"Two goals is frustrating anyway. They decide the game today and there's things to improve on."
Carrick had asked for United's hierarchy to make more signings after a relatively quiet transfer window.
Debutants Youri Tielemans and Andrey Santos were both anonymous in midfield before being hauled off by Carrick in the second half.
United have agreed a deal to sign Brighton midfielder Carlos Baleba, but more new recruits will be required on the evidence of this lacklustre display.
"One game doesn't change the direction of everything. It doesn't change the direction of the football club," Carrick said.
Asked about Baleba's impending move, Carrick added: "I had all eyes on this today so any other player, until he's ours, it's not for me to comment on."
United captain Bruno Fernandes, who set the Premier League's single-season assist record last season, struggled to impose himself and wore a furious expression well before the final whistle.
Fernandes wasn't alone in showing his frustration as United's angry fans made their feelings known.
"We understand the frustration, every season at the start we want to compete and win every game but we need the fans on our side, and to believe in ourselves," Fernandes said.
"We know in the Premier League these types of away grounds are difficult to play against. You need to match their intensity and aggression. The two set pieces ended up costing us the game today."