Wahab Riaz has said that England's middle order is "fragile", ahead of the first Test at Lord's, and believes Pakistan can put pressure on them.

Wahab felt much rested on the shoulders of Alastair Cook, and Joe Root, who has been promoted to No. 3, with the next two positions being filled by James Vince and the recalled Gary Ballance.

Vince managed just 54 runs in four innings in his debut series against Sri Lanka, while Ballance is set to play his first Test in a year, having earned a surprising call-up as England reshuffle their order.

"We know that England is struggling with their middle order, Joe Root is one of their best players and he has to take the responsibility, so that's why he is at No.3," Wahab said. "But I think the other batting is fragile. If you get Cook and Root quickly, you can really put pressure on them, but you can't take things easy against them."

While Wahab, who went a long way in cementing his Test spot with a fiery spell of reverse swing on the second afternoon against Sussex, is correct to pinpoint the uncertainty around the No. 4 and 5 positions heading into the series, England's lower middle-order has been prolific of late. However, they are likely to be tested more by Pakistan's attack - sharp left-arm pace complemented by the legspin of Yasir Shah - than they were by the Sri Lankans.

Jonny Bairstow, who has been in stellar form, has led the way, while Moeen Ali struck a career-best 155 against Sri Lanka at Chester-le-Street. Moeen will be followed by Chris Woakes who has made half-centuries in Tests and ODIs this season. Ben Stokes, who was left out of the squad for the first Test as he continues his return from knee surgery, is expected to be back for the second Test at Old Trafford.

The statistics back up the recent divide between England's top order and the security provided by those lower down: since May last year, their average for positions 1-5 is sixth in Test cricket (Pakistan's batsmen average 14 runs more per wicket, albeit in far fewer Tests, and all of them in Asia) but for positions 6-11, England are top of the pile.

Ahead of the squad being named, there was a suggestion that Stokes could be included to play as a batsman while Jos Buttler's name was also linked to a batting position following his impressive limited-overs form. Buttler subsequently broke a finger playing for Lancashire, so will now not be an option during the Test series, but Pakistan's coach Mickey Arthur said he had been preparing for that duo to be in the line-up.

"We obviously looked at the squad with a lot of interest," Arthur told ESPNcricinfo. "Ben Stokes and Jos Buttler are guys that can take the game away of us, so, though it's not a relief, we were preparing for an England middle order of Bairstow, Stokes and Buttler. But the guys that have come in have earned their opportunity and must have done something right, so certainly won't take them lightly."