Gareth Southgate has warned England not to underestimate Poland in Wednesday's World Cup qualifier after Bayern Munich striker Robert Lewandowski was ruled out with a knee injury.
Lewandowski is widely regarded as one of the world's top forwards and would have posed a threat to England's 100 percent start to the qualifying campaign.
Poland's record goalscorer will miss the Group I clash at Wembley with a knee ligament strain that is expected to sideline him for a month.
Adding to Poland's problems, Mateusz Klich, Lukasz Skorupski, Kamil Piatkowski and Grzegorz Krychowiak all recently tested positive for the coronavirus.
Krychowiak is now expected to feature after a subsequent negative test on Tuesday.
Poland's troubled preparation could leave them vulnerable against an England side who are heavy favourites to win the group after opening the campaign with victories against San Marino and Albania.
But England boss Southgate is determined not to let his players get complacent.
"Poland have got some excellent players and we would be naive to think they would be less of a threat," Southgate told reporters on Tuesday.
"If we take our foot off the gas for one minute we will be hurt. We need to be ready for the game, which we are. A team isn't just about one player and we have to prepare for the highest level.
"I have played Polish teams before. They fight for the cause, they're a proud country, they're a good football team.
"They've got high motivation. We all know this is a key game in the qualification group."
Southgate will have one of his own key players available after playing down injury fears over Chelsea midfielder Mason Mount, who produced influential displays in the previous two qualifiers.
The 22-year-old missed part of training on Tuesday, sparking concerns that he would be ruled out of the Poland game.
But Southgate said: "He didn't warm up with the team but he did the rest of the session with the team.
"He should be fine. They are all available as far as we are concerned."
As he showed with a predatory goal to break Albania's resistence, England captain Harry Kane remains their main hope of winning the delayed Euro 2020 later this year.
Kane's future is unsettled after a difficult season for Tottenham, with Paris Saint-Germain, Manchester City and Manchester United all potential suitors for the striker.
Asked if a protracted transfer saga would prove a distraction for Kane during the Euros, Southgate said: "I had a chat with him, as I do with all of the players when they come into the camp, and he's very positive about the club.
"He was talking about only being a couple of points off the Champions League, in a League Cup final and you can see his focus in the game the other day.
"Harry is, of course, a highly motivated player and all players want to win. I've got no worries about Harry. He's a fantastic professional. He's so focused."
In their 20th meeting with England, Poland are hoping to beat them for only the second time and the first since 1973.
Lewandowski's absence makes the challenge of winning in England for the first time even tougher.
But Poland's Southampton defender Jan Bednarek believes they can still cause an upset.
"This is a big disappointment that Robert will have to have a break for a long time," Bednarek said.
"It's going to be an even bigger motivation for us, for our team to prove that we have quality and we can perform without our own best player, without first level players.
"Lots of courage, lots of motivation to prove to everyone that we can cause many problems to England's team because these are amazing players which I know from the Premier League."