Afridi admitted he could not cope with the mental pressures of Test cricket
England captain Andrew Strauss has admitted his shock at Shahid Afridi's decision to step down as Pakistan Test skipper after one match at the helm.
Afridi ended a four-year exile from Test cricket to lead Pakistan in their 150-run loss to Australia last week.
But he quit immediately following that match, with Salman Butt named as his successor for the series against England, which starts later this month.
"I was surprised. It will put a strain on the Pakistan team," said Strauss.
"It happened so suddenly and it seems strange to be made captain and then to resign after one Test match.
"But he has got his reasons for it and if he does not feel that he is worth his place in the side or he is not enjoying the format, then the worst thing you can do is continue to captain when your heart is not in it.
"Salman Butt is going to have to take over the ropes and keep them on an even keel. Over the last few years there has been a lot of upheaval for Pakistan."
Afridi explained that he "did the wrong thing" in agreeing to return to Test cricket and captain the Pakistan Test side, saying: "I think my temperament is not good enough."
The all-rounder was given the captaincy in the wake of Pakistan's dismal tour to Australia last winter where they lost every international fixture.
Pakistan subsequently gave indefinite bans to former skipper Younus Khan and Mohammad Yousuf because of dressing-room disharmony and although the bans were then lifted, Yousuf decided to retire and Younus was not selected for the current tour.
Afridi alluded to the internal problems in the dressing room that have plagued the Pakistan side this year, admitting: "We need experienced players in these English conditions. We need Younus Khan."
Despite all this, however, Strauss insists his side are still preparing themselves for a tough four-Test series, the first match of which gets under way at Trent Bridge on 29 July.
"We are not expecting anything other than a very motivated and talented side," he said.
Kevin (Pietersen) has not scored as many runs as he has done in the past. But he is a high-quality cricketer and he will come back and play match-winning innings for us
"It is a step up in competition and, with half an eye on the Ashes [which starts in Australia in November], it is important we win as many of these games as possible. It is a big challenge for us, and one we are not going to shirk from.
"It is important we play good solid cricket from the first day of the first Test and hopefully and if we play consistently enough, it should be enough to register a win."
The series also provides an opportunity for key England batsman Kevin Pietersen to regain some form after a lean spell of scores of late.
The South African-born batsman, who recently became a father for the first time, has failed to score more than 50 in his last 17 one-day internationals for his country, though he did score a couple of half centuries in the two-Test series against Bangladesh this year.
"Kevin has just turned 30 but he has got a lot of cricket left in him," said Strauss. "He has had a tough time, there is no doubt about that.
"He has not scored as many runs as he has done in the past. But he is a high-quality cricketer and he will come back and play match-winning innings for us.
"He has had a bit of a break and that has been well received. A new addition to the family changes your priorities a bit and you need to get your life in order. I think he will come out and play really well against Pakistan.
"Kevin wants to be a great cricketer and he knows the way to do that is by scoring runs consistently and putting in match-winning performances and I have no worries that he will do that."