Henri Lansbury does not think England's Under-21 team can afford to get carried away despite taking control of their Euro 2013 qualifying group with a 4-0 victory over Belgium on Wednesday.
England sit eight points clear of Norway, although the latter have two games in hand and play the Young Lions in the final match of the group stage.
The midweek win in Middlesbrough eliminated Belgium, the only team to have taken points off England so far with a last-minute defeat in Mons in November.
An easy win at The Riverside was enough to eradicate memories of that result.
"The lads have been on fire in training and that showed because every time we went forward we looked dangerous," said Lansbury, who scored either side of Stephen Caulker's header before Alex Oxlade-Chamberlain added an injury-time penalty.
"We're in a very good position now but we can't get sloppy," he added. "We now have to focus on the next game and get the three points."
England travel to Azerbaijan in September, where a win will ensure they top the group and progress to the play-offs, before facing Norway at home four days later.