Hussain: Brook 'nailed on' to be in England's XI at T20 World Cup
The 23-year-old Brook arrived in Karachi with just four caps.
But the Yorkshire batsman has been in superb form during the opening matches of a T20 series against Pakistan, scoring 154 runs in three innings at a blistering strike-rate of 194.93.
That tally includes a match-winning 81 not out in a 63-run win on Friday that gave England a 2-1 lead in the seven-match contest. Brook faced just 35 balls while displaying a wide array of strokes from lofted drives over the covers to unorthodox ramps over his shoulder.
"Going into this series, you were thinking, 'How do we get Brook into the World Cup starting XI?' I can't see how you can leave him out now, I really can't," Hussain told Sky Sports ahead of next month's global showpiece in Australia.
"For me he's absolutely nailed on in the number-five spot for the first game in that World Cup. He's going to be a superstar in all formats," the former England batsman added.
"There's no area where you're safe. Batting at five is not an easy position... but every time he's come in at five he's been prolific."
England stand-in captain Moeen Ali, leading the tourists in place of the injured Jos Buttler, was equally enthusiastic about the team's rising star.
"Brooky is showing how special a player he can be. He looks an amazing player and hopefully he grows and becomes one of those top, top players," he said.
Brook himself said there was no great secret to his approach.
"I just try to watch the ball and hit it. It's as simple as that," he said. "When I start doing badly, that's when I start predetermining stuff and overthinking.
"If they go wide, I try and hit it over point; if they go straight, I'll try and hit it over midwicket. I just play the ball on its merit."
