With three convincing victories behind them, Lancaster's men are in irresistible form and are now odd-on favourites to win their first Grand Slam in a decade.
But while the likes of Manu Tuilagi, Chris Robson and Owen Farrell have been in superb form, winger Ashton has been a shadow of his former self with just one try in his last eight Tests - and he was one of the key culprits in Wesley Fofana's try for France at the weekend.
Lancaster has now openly warned Ashton that he could be benched.
"I think he's trying hard and working hard but equally he knows there are areas of his game he's got to work on," said Lancaster.
"We've been talking to him about that. Like everyone else he'll be disappointed by the try Fofana scored."
Saracens star David Strettle, whose England career has been hampered by a string of injuries over the years, is tipped to get Ashton's spot on the wing - but Lancaster claimed that is only one of the ideas he is toying with.
"One of the options is that Manu (Tuilagi) could play there (on the wing) with Billy Twelvetrees at No12.
"That would put some pressure on him, wouldn't it?"
Former England backs coach Brian Smith believes that there is another man in the frame as well: London Irish's uncapped winger Marland Yarde.
"Marland is a better player than Chris Ashton and he would be a better bet against Italy," said Smith.
“Ashton redefined wing-play when he crossed codes from rugby league Wigan in 2007. He’s a very effective finisher. But Ashton doesn’t get his hands dirty the way Marland does, getting involved in the nitty-gritty of games."
Regardless of whether Ashton starts, one thing is apparently certain, at least according to the bookies: England are such hot favourites to beat Italy at Twickenham on Sunday that the best odds you can get are 1-100.