Ashton was banned for a week after accruing three yellow cards in the Aviva Premiership this season, all of them for dangerous tackles or off-the-ball charges.
In passing judgment, the Rugby Football Union's disciplinary chief Judge Jeff Blackett instructed Ashton to work on his tackling technique.
But the incidents against London Irish, Exeter and Northampton were as much about ill-discipline as poor execution and Lancaster has had a word with Ashton.
"I have had a chat with him about both areas," Lancaster said.
"One of Chris's real strengths is his competitive nature. It is tempering that to make sure we get the best out of him and, alongside that, work on his tackle technique.
"He is more disappointed than anyone that he is not available. He has to deal with it and put that frustration to bed and work on those two areas to make sure he is ready for next week."
Ashton will come back into the equation to face Australia at Twickenham on November 17 but England must go into the Fiji game without their most potent try-scoring threat.
The dual-code international has touched down 15 times in his 26 England Tests, although he has not crossed the whitewash since Lancaster took charge.
Ben Foden is the only wing to have done so, and while Lancaster would relish having more out-and-out finishers at his disposal, he is not concerned that Ashton's absence will leave England impotent against Fiji.
England are primed to go into battle on Saturday with Ugo Monye and Charlie Sharples on the wing and Alex Goode offering a ball-playing presence from full-back.
The injury-enforced absence of Jonathan Joseph leaves England with a likely midfield of Manu Tuilagi and Brad Barritt, playing outside the probable half-back combination of Toby Flood and Danny Care.
"You cannot just manufacture finishers. They come through the Premiership and we aim to pick them from there," Lancaster said.
"There aren't many world class finishers around anywhere. We think we have two (Ashton and Foden) but they are unavailable.
"The spark doesn't have to be on the wing.
"Danny Care, Ben Youngs, Alex Goode, Toby Flood, Owen Farrell - there are lots of playmakers in our team, people who can change the course of a game.
"The game is not just won by game breakers. You can break a game by scrumming and scrumming, mauling well, kicking your points. That's what makes a winning team. We have to get that balance right."
It is a mark of the respect that Lancaster has restored in the England team that Twickenham will be sold out for the Fiji game, with 80,000-plus representing a record autumn crowd for tier two opposition.
With that support comes expectation. England signed off their RBS 6 Nations campaign with a 30-9 victory over Ireland which left Twickenham rocking.
After Fiji, England host Australia, South Africa and New Zealand on consecutive weekends in the most challenging test of Lancaster's regime.
His young England side learned some brutal lessons in South Africa during the summer but Lancaster refuses to consider this autumn as just another stage on the development curve.
"I have said to the players 'this is production time now'," Lancaster said.
"We are confident. The challenge is the strongest one we have faced against one, two and three in the world but we need to find out where we are and where we stand.
"The support we have had on and off the field has been fantastic. People have responded well to a new England team.
"Now it is about production time and delivery time and we want to make sure we do that at home.
"Four games at Twickenham, all sell-outs. It doesn't get any better against the top three in the world."
Lancaster's challenge this week is to ensure the England squad treat the Fiji game on its own merits and do not fall into the trap of viewing it as a stepping stone to the three southern hemisphere big guns.
"We are not thinking that way. The danger that sets is that you are looking to game two before you have completed game one," he said.
"It is about getting into detail now about Fiji and getting the mindset right and the organisation right so we are ready to go.
"Our objective is to get ourselves in the right place technically and tactically so we can deliver a winning performance."
Ashton will be available to face Australia a week on Saturday and so too, Lancaster believes, will Joseph and Alex Corbisiero.
Joseph, the London Irish centre, failed a fitness test on an ankle injury this morning and is unlikely to train before Lancaster names the squad to face Fiji on Thursday.
Corbisiero is set to play for the Exiles this weekend after overcoming a knee injury and he is expected to be in contention to face the Wallabies.
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