Ireland head coach Andy Farrell says he needs to examine the part he played in his side's 24-12 defeat to England in their Six Nations game at Twickenham.
Ireland trailed 17-0 at half-time and despite improving after the break, their hopes of winning a Grand Slam or the Triple Crown ended by the loss.
"I need to look at myself regarding the performance in the first half because obviously we weren't in the right area.
"We didn't play how we wanted to play until the game was over," said Farrell.
Defensive errors by captain Johnny Sexton and wing Jacob Stockdale allowed George Ford and Elliot Daly to cross for first-half tries and gift England tangible reward for their superiority, especially up front.
Sexton was unable to collect Ben Youngs' grubber kick behind his own try-line, allowing Ford to score, while Stockdale was shrugged off the ball by Daly, who grounded for England's second try.
Sexton also missed relatively straightforward kicks for a penalty and a conversion in the opening 40 minutes as any ambitions Ireland had of continuing their winning start to the tournament dissipated.
A second-half try from Robbie Henshaw and a late touchdown by replacement prop Andrew Porter gave the final score a somewhat flattering scoreline for the visitors.
Ireland do at least still retain hope of winning the title with games at home to Italy and away to unbeaten France still to come in March.
"We certainly didn't come out of the blocks - there was only one team that did that and that is bitterly disappointing," Farrell told ITV Sport after the match.
"We got a bit of a reaction in the second half but I thought England were excellent, they were fighting to stay in the championship.
"Every side will look at themselves physically and they certainly won that battle. That's disappointing for us because we try to pride ourselves on that sort of thing.
"We came off second best in that area and we didn't fire a shot in the first half."
'England put it up to us' - Sexton
Sexton agreed Ireland were left with plenty to ponder after the defeat, which followed victories over Scotland and Wales in their opening two games.
"We gave a very good team two tries from our mistakes and didn't cover the chip-kick, which we knew was going to come," said the Ireland fly-half.
"We were getting the ball on the back foot and trying to get the ball to the space on the edges but we couldn't get it there so we were made to look a bit silly at times.
"We have to have a look at a few things off the top of the line-out - we seemed to be past the midline of the line-out before we even got the ball. I'm not sure what was happening there but we need to try and be better.
"We need to try and not play in certain areas of the field when we are going backwards. We compounded a few errors and we have a lot to learn from.
"When you come to a place like Twickenham the atmosphere is incredible. Fair play to England, they put it up to us."
Ireland lie third in the Six Nations table, four points behind France and level on points with second-placed England.
"We have a big home game against Italy in a couple of weeks and if we can do the business there we still have a championship to play for so we have to pick ourselves up pretty quickly," added the Ireland skipper.