Adrian was one of few Hammers players to emerge from the first leg with any credit.
The Spaniard was one of few Hammers players to come out of Thursday's 2-1 defeat to NK Domzale with any credit, after pulling off a superb double save late on in Slovenia.
Matec Crnic's double, either side of a Mark Noble penalty, was enough to hand the minnows an aggregate lead heading into the second leg, which will be West Ham's first at the Olympic Stadium.
And Adrian has assured supporters, who look set to sell out the fixture, that he and his teammates will put on a show as they look to progress to the play-off round.
"We will work harder to come back next thursday in our stadium and fans," the 29-year-old posted on Twitter.
We will work harder to come back next thursday in our stadium and fans⚒— Adrián San Miguel (@AdriSanMiguel) 28 July 2016
Trabajaremos más fuerte para remontar! pic.twitter.com/TxVYi5d2tX
Hammers boss Slaven Bilic was forced to field a makeshift side in Domzale, with his back line particularly afflicted.
Winger Michail Antionio struggled at right-back, while Sam Byram was shunted into an unfamiliar left-back role, with midfielder Havard Nordtveit dropping to the heart of defence.
And they are likely to be patched up again in Stratford, with no new signings able to be registered until after the round is over.