England coach Eddie Jones says "it does not get much uglier" than his side's display in the 19-16 win over France.
England secured a record 15th straight victory but looked well below their best as they made a winning start to their Six Nations title defence.
"We weren't our usual urgent selves and maybe I've got to look at the preparation I gave the team," said Jones.
"The performance was ugly, but the result is beautiful."
England's campaign continues with a trip to Cardiff to face Wales next Saturday, and Jones has demanded an improvement from himself and his squad.
"I felt some players were still in their club mentality so that's something we need to work on - I don't think I prepared the team as well as I could have done," he added.
Neither wing Anthony Watson or second row George Kruis are expected to have recovered from injury in time to face Wales, but Jones may be tempted to change his starting XV anyway after the impact made by his replacements.
Front-row forwards Matt Mullan and Jamie George, flanker James Haskell and scrum-half Danny Care all impressed, with centre Ben Te'o also coming off the bench to cross for the match-winning try in the 70th minute.
"The finishers made a fantastic impact on the game, we got really good value from them and that is the strength of our team, we have a brilliant 23-man squad," added Jones.
Captain Dylan Hartley echoed his boss, saying "a huge amount of credit needs to go to our finishers today".
"Ben Te'o and James Haskell came on and gave us a good bit going forward at the end there so unbelievable impact from our subs," he added.
"We dug in, we found a way and we'll take something from that."
|England's remaining fixtures|
|11 February||Wales (a)|
|26 February||Italy (h)|
|11 March||Scotland (h)|
|18 March||Ireland (a)|
Former England scrum-half and World Cup winner Matt Dawson: "France were better than England in a lot of areas, but the strengths of Eddie Jones' side is their fitness and ability to play under pressure.
"They are unbeaten for the last 15 games, so it was always going to be tough for France to take it through to 80 minutes.
"The substitutions for England were the difference in the end. The battle of the bench belonged to England."
Former England hooker and Grand Slam winner Brian Moore: "France were the better team for the most part. But they could not put away the several breaks they made. With one moment of clarity, England managed to go ahead.
"They say just win your first game and England did just win their first game."