Sam Allardyce admitted mistakes had cost his West Ham United team dear in Saturday's 3-0 Barclays Premier League defeat at Swansea City.
Individual errors cost the Hammers dear at the Liberty Stadium as uncharacteristic slips from Jussi Jaaskelainen and James Collins gifted the Swans a 2-0 lead.
West Ham created enough opportunities to get themselves back in the game before half-time, only to be denied by a succession of blocks and saves. Swansea then put the game to bed with a third goal midway through the second period.
Big Sam conceded that his players had given themselves too much to do by shooting themselves in the foot after making a bright start in south Wales.
"There is nothing you can do or say to defend the players who made those mistakes because they were such major errors in terms of what we were trying to do at that time in the game," said the manager.
"We started the game very, very well and were looking very dangerous and very solid and sound at the back and unfortunately the goalkeeper has made a mistake on the first real attempt by Swansea to get into our box and they went 1-0 up.
"If one mistake is not bad enough, to make two like the one made by James Collins - which was very unusual for him - then you've got no chance. We were away from home and we tried to get back but it was too difficult and in the end we have thrown the game away by our individual errors getting punished.
"We had enough opportunities to get ourselves back into the game when we were 2-0 down but we didn't get one and that made the second half much more difficult for us. Swansea are very good at keeping the ball and they didn't have to try to score any more. They just had to keep the ball and play the game out, which they did very well."
What made the Hammers' defensive meltdown all the more surprising and frustrating was the fact that they were mistakes by two vastly-experienced players that led to the club's first away defeat since 31 January.
"These were two of our new players. Of course I have known Jussi a long time and he has a huge amount of Premier League experience so I didn't expect him to make that error.
"It was the same with James. He's been in the Premier League a long time and he knows what it's all about, but players make mistakes and unfortunately two came within a short space of time that put the game beyond us and that's the disappointing thing for me.
"Having a good, solid defensive unit last week, I didn't expect to see those type of errors but they've happened. We've been severely punished and we must take it on the chin and bounce back immediately, starting with the cup game against Crewe."
With the Capital One Cup second-round visit of Crewe Alexandra on Tuesday and a Barclays Premier League date with Fulham at the Boleyn Ground on Saturday, Big Sam said the Hammers had no time to dwell on their defeat in south Wales.
The managed hinted that the likes of new boys Alou Diarra and Modibo Maiga, as well as James Tomkins, Matt Taylor and Nicky Maynard, would all be given opportunities to stake their claims for a regular starting place in the midweek cup tie.
"We've still got to come to terms with the Barclays Premier League. We've got new players who need to feel their way in and that does take some time. In the midst of that, we've got to make sure we get results while they settle in - particularly the lads from abroad who are getting to know each other.
"We'll get better as time goes on but it's very important that we try to get results from the very start and this was a big setback for us. While we know Swansea was going to be a very difficult game and they are very good at home, the way we started this game and the way we gifted it to them was a big let-down for me and the lads.
"We've got players like Alou Diarra, who we gave a taste of what the Premier League is all about, who will come into the frame for Tuesday. James Tomkins needs to catch up on games because he didn't get them at the Olympics.
"Gary O'Neil, Joey O'Brien, Nicky Maynard and Matt Taylor are among the players who will play with a huge amount of first-team experience. We'll only give one or two of the younger ones a game, but not too many.
"We're going to field a team that is good enough for me to beat Crewe Alexandra and then we'll move on to Fulham and try to put this one behind us with two positive results at home in the next week."