Former England scrum-half Matt Dawson is “utterly baffled” by England head coach Eddie Jones’ selections at number nine in the run-up to the World Cup.
Gloucester’s Willi Heinz, 32, could become the fourth scrum-half to make his international debut under Jones when England face Wales on Sunday.
Ben Youngs is England’s starting nine, while experienced international Danny Care last played in November 2018.
“I don’t how to read into it,” said Dawson on BBC Radio 5 Live.
“If Ben Youngs goes down before [England’s World Cup pool match against] France, that number nine has got to run the show.
“Potentially you have someone with two or three caps going into that scenario. I need someone to explain it to me.”
Heinz, who was born in New Zealand but qualifies for England through his late grandmother, has played for Gloucester since 2015 and was integral to the side’s run to the Premiership play-offs last season.
Jack Maunder, Ben Spencer and Dan Robson have also been given their first cap by Jones, who is yet to settle on a back-up for Youngs since leaving Care out of his squad.
Spencer looked a likely option when he was included in a training camp in Italy at the end of July, but the Saracens scrum-half has not been chosen for the warm-up match against Wales at Twickenham.
The choice seems more significant given that the England head coach will name his World Cup squad the day after the match, almost four weeks before the deadline of 8 September imposed by World Rugby.
Jones’ side will then play another warm-up game against Wales in Cardiff before facing Ireland and Italy.
Who will play in England’s back row?
Another key selection area for Jones will be the back row, with Brad Shields now a doubt because of a foot injury which could mean he does not play again before England’s first World Cup game on 22 September.
Harlequins’ Alex Dombrandt had replaced Shields in the training squad, but has been left out of the group to face Wales, and experienced former captain Chris Robshaw does not feature in Jones’ plans.
At number eight, Billy Vunipola is the only specialist in the group given that Nathan Hughes was not included in the training squad.
All this means Sale’s Mark Wilson, who made his debut for England in 2017 and can play flanker and number eight, is now “one of the first names on the plane” according to BBC Rugby union correspondent Chris Jones.
“Wilson really has come from nowhere,” Jones added on BBC Radio 5 Live Sport’s Matt Dawson’s Rugby Show.
“A year ago we weren’t talking about Mark Wilson and now he is integral to England’s World Cup hopes.”