Rugby League World Cup 2013: McNamara rues England defeat
England coach Steve McNamara said he was left to wonder "what might have been" after their 28-20 defeat by Australia in the opening game of the 2013 World Cup.
His team led 10-0 but could not hold on and have now lost their last seven matches against the Kangaroos.
"There are a lot of positives but there is a real sense of frustration that we did not finish the job," said McNamara.
"We are sat there wondering what might and should have been."
England have not beaten Australia since the opening game of the 1995 World Cup, a 20-16 victory at the old Wembley Stadium.
Tries from Ryan Hall and Leroy Cudjoe saw England take control of Saturday's match under a closed roof at the Millennium Stadium in Cardiff.
But they were punished for a series of unforced errors and sloppy penalties, and always trailed after succumbing to an 18-10 deficit at the break.
"Every time we got to the right end we troubled the Australians," added McNamara, who took over as England coach in 2010.
"We had to cling on at times. We started superbly and had great energy but we gifted them too much possession, gave a lot of penalties away and some easy field position."
Australia are now likely to finish top of Group A, giving them a theoretically easier route to the final in Manchester on 30 November.
In contrast, England are likely to face a semi-final against current world champions New Zealand if results go to form.
"We think we can beat this Australian team and we have got a lot more left in us," added the England coach, whose side play Ireland in a sold-out fixture in Huddersfield on 2 November.
"I have always felt we have a team capable of winning the competition."
England's preparation included a warm-up defeat against Italy, and internal discipline issues that led to Gareth Hock's expulsion from the squad and saw prop James Graham allegedly dropped for the match against the Kangaroos after breaking an alcohol ban.
McNamara himself walked out of Friday's press conference after he was repeatedly asked about the incidents.
The 42-year-old said once again on Saturday that none of this has affected his team's preparation for the game, while Australian coach Tim Sheens was full of admiration for England's performance.
"We were not at our best," said Sheens, whose team did not play a warm-up game and looked rusty in the opening stages.
"But I do not want to take away from the English performance, they came out and were aggressive.
"We've got some work to do but England came to play, especially given the issues they supposedly had, [and] they performed really well.
"To be honest, they outplayed us in some areas - it was not easy. It was close and I was on the edge of my seat. It was a game that was not over at any stage."