England manager Gareth Southgate has admitted that his side "still have a lot to do" if they are to qualify for the 2018 World Cup in Russia.
The Three Lions moved four points clear at the top of Group F with a 2-0 victory over Lithuania on Sunday and are now the only team yet to concede a goal during the qualifying campaign.
England are overwhelming favourites to win the group, thereby claiming the only automatic qualification place, but Southgate warned that there are plenty of tests still to come for his side.
"The group is in our hands, which is the most important thing. We still have a lot to do," he told reporters.
"The home games (against Slovakia and Slovenia) are the important ones for us in terms of direct opposition in positions two and three at the moment.
"But we know what going to Scotland is going to be like and we have to go and play on a plastic pitch in Lithuania. There's still plenty to do and also we have got to keep looking to improve with every performance."
England's next match is away to Scotland in June.
