In a nerve-shredding atmosphere, Luciano Spalletti's Juventus actually led 2-1 at half-time after Teun Koopmeiners replied to Brazilian midfielder Gabriel Sara's opener with a brace of his own.

But Colombian full-back Juan Cabal was dismissed for two bookings in a calamitous second half as Lang's brace and goals from Davinson Sanchez and Sacha Boey sunk the Old Lady, who faced a miserable return to Turin.

Sara opened the scoring with a slick left-footed strike from just inside the box on 15 minutes, but that lead was short-lived.

Gala goalkeeper Ugurcan Cakir could only parry Khephren Thuram's powerful header into the path of the onrushing Koopmeiners, who tapped in the leveller just a minute later.

Koopmeiners then picked out the top corner from the edge of the box on 32 minutes after a clever exchange with US midfielder Weston McKennie.

That was as good as it got for the visitors, though.

Okan Buruk's Turkish champions ran riot after the break as Lang pounced on a loose ball in the six-yard box to level on 49 minutes.

Sanchez nodded Gala ahead on the hour mark as the home fans ramped up the volume.

Juve complained of an unfair dismissal in their 3-2 defeat to Serie A leaders Inter Milan at the weekend, but they could have no issues with Cabal's sending off on 67 minutes.

Lang bagged his brace shortly afterwards and substitute Boey ensured Gala will take a commanding lead to Turin next week as he lashed home from an angle five minutes from time.