England head coach Eddie Jones insists his focus is on ensuring his side peak at the 2019 World Cup and not on maintaining his current unbeaten record.
England have won all 13 of their matches under Jones, claiming a Six Nations Grand Slam, whitewashing Australia 3-0 on their summer tour and producing a clean sweep in their four autumn internationals.
That came off the back of a wretched 2015 World Cup campaign under former head coach Stuart Lancaster, when England failed to progress from their group despite being on home soil.
Jones admits sustaining his perfect record throughout 2017 may be an unrealistic aim and says the long-term ambition is to mount a serious challenge at the next World Cup in Japan.
"At the end of the day, sooner or later we'll lose a game, losing a game is not the end of the world, it's a great learning experience and when we lose a game it will be part of the learning experience," Jones told Sky Sports News HQ.
"We want to get better as a team and our aim is to peak for the World Cup."
When asked whether he thought England could win the World Cup in 2019, Jones added: "100 per cent."
Jones also heaped praise on captain Dylan Hartley, who succeeded Chris Robshaw in the role in January.
"Look, after I decided it was going to be Dylan, I was 100 per cent sure that he was going to do a good job," he said.
"How good a job, I didn't know. But I knew he was going to do a good job, he's a committed guy, a driven guy and he has certainly shown that."
Asked whether he had a replacement in mind if Hartley suffered an injury prior to the Six Nations in February, Jones said: "Yes, but I am not going to tell you."