Sept 1 (Reuters) - Manchester United winger Jadon Sancho is a major doubt for England"s World Cup qualifier against Hungary on Thursday due to injury, manager Gareth Southgate said on Wednesday. Southgate did not reveal the extent of the injury but said Sancho had sustained a knock in training. The encounter in Budapest will be England"s first game since their defeat by Italy in the Euro 2020 final, with Southgate saying the team were focused on starting all over again. "The team have gained confidence from what they"ve achieved and the progress they"ve made, not only this summer but over the last four years. But equally, we have to start again," he told reporters. Southgate said he expected a difficult game against Hungary, who are second in Group I, two points behind England. "Mentally, it"s a good test for us. We"ve got to go away from home now, in front of 60,000 fans and a very good team... (Hungary) sit second in the group and took points off Poland in March and took a point off France and Germany in the summer." Centre back Harry Maguire urged his team mates to show their mental resilience in what will be the first of three games for England this month. "It"s a big test, more mentally than physically, but it"s one us players need to look at and we"ve spoken about as players and we need to be ready," said the Manchester United skipper. After the trip to Budapest, England take on Andorra at home on Sunday and then face Poland away on Sept. 8.