England's white-ball coach Matthew Mott said the Twenty20 series defeat to South Africa was a "line in the sand" after they ended the home summer without a limited-overs series win for the first time since 2013.
The 90-run loss in Southampton on Sunday gave South Africa a 2-1 win, raising concerns about England's form heading into this year's T20 World Cup in Australia.
Since Eoin Morgan's shock retirement from international cricket in June, India have beaten England in both limited-overs competitions while the ODIs with South Africa ended level following a washed out finale in Manchester.
"It was disappointing. I thought we put ourselves in a good position to win the series and we'll have to take a lot out of that game," said Mott, who took charge in May following Chris Silverwood's resignation.
"I've just spoken to Jos [Buttler] very briefly and this is a line in the sand moment for the team."
England travel to Pakistan for seven T20s starting in September followed by three games against Australia, before opening their World Cup campaign against Afghanistan on October 22. However, the Three Lions will be worried about their loss of form in white-ball cricket, even as their Test team has started to turn things around under the new leadership of Ben Stokes and Brendon McCullum.
"We'll want to draw some experience from and use The Hundred really well to get that confidence so when we get ready for Pakistan and the World Cup we're a bit of a different team," said Australian Mott.
Captain Buttler admitted successive defeats at home have dented the team's confidence.
"I can be honest enough to say we haven't performed how we would have liked the whole summer, so maybe the confidence has taken a bit of a dent," the wicketkeeper-batsman said.
"We have faced some challenging conditions at times but as individuals and as a team you must try to turn up every day with a fresh outlook playing the conditions in front of you trying to impose yourselves on the game. We haven't managed to do that as well as we would have liked.
"For us as a group we now go away from being a team for a bit and a lot of players will go into The Hundred, which is going to be a great tournament for everyone involved.
"With the World Cup not far away, performances in The Hundred and trying to stick your hand up and showcase your best in a high pressure environment and in a big competition is probably the best thing for everyone in the group."
