Ruaridh McConnochie could be robbed of his full England debut for the second weekend running.
The Bath Rugby back was picked to play against Wales at Twickenham last Saturday, only to pull out after suffering a minor hip injury in training.
This week, he has been picked to start against the same opposition in Cardiff on Saturday (2.15pm), but now he has a new fitness doubt.
Head coach Eddie Jones has told BBC Sport the 27-year-old will be assessed on Friday night to see if he is ready to win his first 15-a-side cap.
"He's just a bit sore," said Jones. "It is not the same injury as last week. We're confident he might recover."
England do not currently have a back-three replacement on the bench; meaning Bath team-mate Anthony Watson or Leicester Tigers winger Jonny May could come into the matchday 23.
Jonathan Joseph, who is starting at 13, and replacement Manu Tuilagi have both filled in on the wing in the past.
Exeter Chiefs' Jack Nowell is still recovering from an ankle injury suffered in the Premiership final against Saracens on June 1.
McConnochie has only played one season of professional 15-a-side rugby after joining Bath from the England 7s squad last Summer.
England have two more World Cup warm-ups after the game against Wales at the Principality Stadium. They will face Ireland at Twickenham on August 24 and Italy in Newcastle on September 6.
England XV to face Wales
15. Elliot Daly (Saracens, 31 caps)
14. Ruaridh McConnochie (Bath Rugby, uncapped)
13. Jonathan Joseph (Bath Rugby, 41 caps)
12. Piers Francis (Northampton Saints, 5 caps)
11. Joe Cokanasiga (Bath Rugby, 5 caps)
10. George Ford (Leicester Tigers, 56 caps, captain)
9. Willi Heinz (Gloucester Rugby, 1 cap)
1. Ellis Genge (Leicester Tigers, 10 caps)
2. Luke Cowan-Dickie (Exeter Chiefs, 12 caps)
3. Dan Cole (Leicester Tigers, 86 caps)
4. Joe Launchbury (Wasps, 59 caps)
5. Maro Itoje (Saracens, 27 caps)
6. Courtney Lawes (Northampton Saints, 72 caps)
7. Lewis Ludlam (Northampton Saints, 1 cap)
8. Billy Vunipola (Saracens, 42 caps)
Replacements
16. Jamie George (Saracens, 37 caps)
17. Joe Marler (Harlequins, 59 caps)
18. Kyle Sinckler (Harlequins, 22 caps)
19. George Kruis (Saracens, 33 caps)
20. Jack Singleton (Saracens, 1 cap)
21. Ben Youngs (Leicester Tigers, 86 caps)
22. Owen Farrell (Saracens, 70 caps)
23. Manu Tuilagi (Leicester Tigers, 33 caps)
