England's batsmen were not good enough during the World Twenty20 win against Afghanistan, according to Eoin Morgan.
England were reduced to 42-4 and 57-6 by the only side outside Test cricket left in the tournament, but recovered to post 142-7 and win by 15 runs.
"The execution of what we were trying to do wasn't good enough today," captain Morgan told BBC Sport.
"We weren't at our best, which allowed Afghanistan in to the game. Ultimately we did enough to win."
England chased 230 to beat South Africa in their previous game, but were on the verge of humiliation against Afghanistan after losing five wickets for 15 runs, including three in an over.
They were rescued by Moeen Ali and David Willey, who shared an unbroken stand of 57 in 33 balls, before Afghanistan were restricted to 127-9.
"Conditions change and scores come down," added Morgan. "You have to show experience and composure, which Moeen Ali and David Willey did to get us up to a defendable total.
"The depth of out batting is one of our strongest suits. We're grateful that we bat deep, but we want the bulk of the responsibility falling on the top six or seven."
England, World T20 winners in 2010, will definitely reach the semi-finals if they beat Sri Lanka on Saturday and South Africa lose one of their final two games.
"There's an incredible amount of talent in this side," said Morgan. "Once we get the right mindset and adapt to conditions, we'll be a strong side."