Eoin Morgan shouldered the blame for England's dramatic one-run defeat to South Africa in the first Twenty20 after holing out to expose the lower order before the final over.

Jason Roy lit the touchpaper to a chase of 178 with a blistering 70 from 38 balls but his departure, with 46 required from the final 34 deliveries, led to England losing their way under the East London floodlights.

After Joe Denly and Ben Stokes were dismissed cheaply, Morgan's thunderous hitting in the penultimate over took him beyond a half-century and left England needing seven runs from as many balls.

However, he was caught on the boundary for 52 from the final ball of Beuran Hendricks' over, much to his annoyance, and England's nerve deserted them in the face of some excellent death bowling from Lungi Ngidi.

Morgan said: "It was in the absolute slot to check down the ground and I've smoked it straight to the man. I was fuming with myself, I hit it way too well.

"It's a mistake, it should never have happened. I should have been facing coming into the last over with six to win.

"But when you lose a game by one run, there are many things you can look at. For us it is a matter of that because the way we played wasn't up to our normal standard, it's almost like it's gone back a bit and I don't know why."

Tom Curran hit to deep midwicket while Moeen Ali was bowled as England succumbed to Ngidi's off-cutters, and with three required off the final ball, Adil Rashid was run out coming back for a second which would have tied the game.

Asked whether a near full-strength England side starting their preparations for the T20 World Cup later this year should have been able to get over the line, Morgan responded: "Absolutely, nine times out of 10.

"But normally when there's not a guy with that sort of skill level of a slower ball, you win that game.

"It's another challenge for us, we'll have to come back and come up with a counter plan or try to target somebody else."

Morgan felt England struggled to get to grips with the nature of the surface at Buffalo Park, where South Africa romped to 105 for one at the halfway stage of their innings.

While Moeen and Rashid took combined figures of two for 45, England's seamers struggled in the early part of the innings before bouncing back at the end to restrict the hosts to 177 for eight.

"I thought adjusting to the wicket – our normal line and length seemed to not bounce at all and slid on to the bat nicely so guys had to bowl a lot shorter into the wicket," Morgan said.

"They found that difficult for the first 10 overs and that's why South Africa got ahead of us, I thought we did well to claw it back. Adil bowled beautifully, Moeen bowled beautifully and probably left them with a par score.

"The chase, I thought we were always in command, particularly when Jason was at the crease, then I sort of continued that on.

"One thing we did speak about at the halfway stage that was evident was that when South Africa had new guys coming in they found it difficult.

"Whether that's the background, the light, whatever it was, it was just every batter that came in found it difficult, you can see that they were late on to the pace of the ball.

"Whether that's contributed to us not getting over the line, maybe, but we need to chat about it."

England have no time to dwell on the defeat as the penultimate T20 of the series is in Durban on Friday.