Wales coach Mike Ruddock pointed to the sin-binning of flanker Martyn Williams as the turning point in their 47-13 Six Nations loss to England at Twickenham.
Referee Paul Honiss sin-bins Wales flanker Martyn Williams
Wales were only trailing 18-13 when Williams was shown a yellow card for deliberately jumping into Lewis Moody.
"The sin-binning of Martyn Williams was a crucial moment, as that allowed England to turn the power on," he said.
"With a 14-man Wales team they really put us to the sword and ran away with it - and that really hurts."
Williams had claimed Wales' first-half try when on hand to support Dwayne Peel's incisive break, and that saw the visitors go into half-time just 15-10 behind.
But England took advantage after Williams was sin-binned by New Zealand referee Paul Honiss in the 52nd-minute for obstructing Moody as the rival flanker jumped for a high ball.
"I genuinely think it was a little bit harsh," Williams said. "Maybe it was a penalty, but he sin-binned me for shoulder-barging and I had my back turned.
"It's just one of those things, sometimes things go for you and sometimes they don't.
"It was a turning point but England did play really well - the guys they were bringing off the bench helped build the momentum for them."
Ruddock echoed his flanker: "A couple of things just weren't going our way.
"For example, from a great turnover Michael Owen threw a pass when we tried to break out and it was called back for being forward.
"At the same time you have to respect that England played some good rugby but that moment went against us. It was a tough afternoon for us.
"I guess we just have to take it on the chin. We dished it out last year when we won the Grand Slam and now we have to regroup quickly for next week against Scotland."
There was further bad news for Wales, already beset by a host of injury problems, as they face losing back-up scrum-half Gareth Cooper for the remainder of the championship after he suffered a dislocated shoulder.
Despite the heavy defeat, Ruddock says there were areas of Wales' play that he believes have improved from last year's win over England in Cardiff.
"Incredibly I thought there were a lot of things there that were better. For example, our scrum was a lot better and our lineout - although with some mishaps - was overall better.
"We didn't make as many breaks, but we know we can play attacking rugby so I think there's still some good signs for this Wales team, even as much as it hurts today."