Marcus Rashford missed England's first training session in Russia on Wednesday as a precaution after picking up a knee strain.
Rashford sat out on the advice of England's medical staff after sustaining what manager Gareth Southgate described on Tuesday as a "slight knock" during the squad's final training session at St George's Park, but the problem is not expected to affect his availability for Monday's opening World Cup match against Tunisia in Volgograd.
"We have another week of preparation and a lot of competition for places, as you know," Southgate told reporters on Tuesday upon arrival at Pulkovo Airport in St. Petersburg.
Rashford also assured fans the problem was nothing serious, tweeting on Wednesday evening: "Thanks for the messages I've been getting. Picked up a slight niggle but nothing to worry about #ThreeLions"
Rashford, who scored 13 goals in all competitions for Manchester United this season, is battling for a starting spot against Tunisia and strengthened his case with a goal in the 2-0 friendly win over Costa Rica on Thursday at Elland Road.
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One player assured of his place is Kyle Walker, who has been deployed by Southgate on the right of a three-man defence despite excelling as a marauding right-back for Manchester City this season.
Walker had hoped to prove himself as the world's best right-back in Russia, but added that he is happy to help England in any way he can.
"I have been playing professionally since I was 18 at right-back," he said. "To get to your first World Cup and probably not playing in your preferred position where you want to showcase your talent is not disappointing, but it is like OK, it is a little bit of a step back.
"I have to move on from it. I'm professional. I've played the game, [being] 28 now, as long as it is for the team, and [if] the manager feels it is going to benefit the team, then why not?"
Walker said the transition has been made easier because of the tactical adjustments Pep Guardiola has made at times that have allowed him to work more in a three-man defence.
"Is it my preferred position? Of course not," Walker said. "I want to play right back. I have worked my whole life to get to where I am now in a World Cup squad, and to showcase my talent in the World Cup stage, playing in my position.
"But I'm a team player. I will do anything for the team. If that means the gaffer thinks to help the team out it is me playing there, I am all for it."
Southgate's decision, Walker said, may even open up a chance for him to refine his skills during the World Cup.
"It might give me a little bit of an opportunity, but it is about reading the game," Walker said. "I don't want to leave space at the back to get on a counter-attack. I'm a defender first and foremost, and if I'm playing right centre-half, I am even more of a defender than the wing backs.
"If I can get forward, I am sure you will see me up there. I have to be professional. I have to manage the game correctly and see what we are doing in the game."