"Immediately after I gave Tendulkar caught by wicket-keeper Matt Prior off Andrew Flintoff I realised from his reaction that I had given a wrong decision," Dar told IANS in an interview here.
Tendulkar, who scored 30 off 46 balls, was visibly stunned and he uncharacteristically stood in his crease for a few seconds, suggesting he had not snicked the ball, before returning to the dressing room.
Batting first, India were reduced to 59 for four with Tendulkar's dismissal and eventually lost the match by seven wickets at Lord's and with it the series 3-4.
Dar, who was here to officiate in the India-Australia One-Day Internationals, said that the mistake had occurred because of a brief lapse in his concentration.
"On that ball Flintoff was very close to bowling a no ball and as I was looking at his foot my concentration was disturbed," said Dar, widely considered one of the best umpires in the world.
Asked if he felt like taking his decision back to enable Tendulkar to continue batting, the 39-year-old member of the International Cricket Council's Elite Panel said that he had never recalled any player.
"Since I had never called any batsman after giving a decision I did not call him back. So, if I were to call Tendulkar I would also call the last man if given wrongly out," reasoned the man from Lahore.
"I knew that match was the decider. And I was upset after giving that decision. It was tough match (for me)," he said, referring to the 3-3 series score before that match.
Dar, however, showed his regret and tried to show his feelings to Tendulkar immediately after the match.
"After the game when players shake hands with the umpires, Tendulkar also shook my hands on the field. As he did that I said to him 'hard luck'," disclosed the affable official, who became the first Asian to officiate in 100 ODIs here Wednesday.
"Players also know that how good an umpire is. They understand that mistakes are not made deliberately and they respect good umpires."
A former first-class player himself, Dar revealed that if he is not satisfied with one of his decisions early in a match it bothers him.
"If I give an erroneous decision early in a match it plays on my mind. But I try not to let that decision affect me for the rest of the match," he said.
Dar, who also officiated the final of the 2007 ODI World Cup, was recently short-listed among the three umpires for the annual ICC's Best Umpire Award, which eventually went to Australian Simon Taufel.
He is thankful to his parents and his wife for their sacrifices to enable him to be away for long periods and concentrate on his job. His work entails him being away from home for seven-eight months a year, which forces him to miss his three young sons.
That is why Dar, who has also officiated in 39 Tests, has decided to quit umpiring at 50, 10 years before the retirement age prescribed by the ICC.



A youthful Indian cricket team, full of vigour and determination, made history here Monday by beating Pakistan by five runs to clinch the Twenty20 World Championship when all seemed lost.
The win - achieved without Sachin Tendulkar, Rahul Dravid and Sourav Ganguly, who all had opted out - also kept India's slate clean against Pakistan in cricket's global competitions. India have never lost to Pakistan in the ODI World Cup - and now in Twenty20 too.
Imran Nazir, who looked in ominous form, and Younis Khan then tried to steady the ship, but after adding only 26 for the third wicket Nazir (33, 14 balls, 4x4s, 2x6) became the target of Uthappa's direct throw after he reacted late to Younis's call for a run off Sreesanth.
As Uthappa attempted to hit over the infielders off left-arm pacer Sohail Tanvir he mistimed the shot and Shahid Afridi at extra cover took a comfortable catch.