Forwards coach Steve Borthwick feels England's competing hookers Dylan Hartley and Jamie George are inspiring one another to reach new standards.
Hartley was made captain by Eddie Jones in one of his first acts as head coach and the move has been a productive one, with England winning 15 Test matches on the bounce.
But George is having a growing influence on matches, replacing Hartley - who had missed six weeks of action through a ban served while he was on duty for his club side Northampton - after 46 minutes of the 21-16 victory over Wales, and the Saracens front row's impact was immediate.
"As the forwards coach of the team it's a brilliant position to be in, to have competition for places. It's what we all want across every position in the team," said Borthwick, who earlier this week described Hartley as a "fantastic" captain.
"I think having that competition means that standards are driven and that players are always looking to improve; those two players definitely do that.
"I think he (Hartley) has done some really good things. There has been an improvement in our scrum and Dylan is clearly central to that. He's played a vital role in our improvement in this tournament."