Second leg is a head scratcher for West Ham boss Slaven Bilic
Bilic's side put in an abject performance in what was their first competitive game of the season last Thursday and were lucky the deficit was not even worse.
Bilic was actually banned from the touchline following his dismissal at the same stage of the competition last year against FC Astra.
The Hammers went 1-0 down on 10 minutes when the referee adjudged Havard Nordtveit had handled in the box and awarded a penalty.
Mark Noble restored parity from the penalty spot but West Ham went on to concede in the second half, failed to threaten the Domzale goal at all and could have lost by more if it wasn't for a fine double save by Adrian at the death.
So what changes does Bilic need to make for the all-important second leg and first ever game at the Olympic Stadium?
West Ham's Lewis Page in action in last season's Europa League
Youth key in defensive reshuffle
Youngster Lewis Page was somewhat surprisingly left on the bench while right-back Sam Byram was deployed as a makeshift left-back to cover for the injured Aaron Cresswell in the first leg. As a result Michail Antonio continued at right-back, much to the frustration of Hammers fans.
Neither covered themselves in glory with Antonio having a shocker and Byram never looking truly comfortable.
Bilic needs to trust in youth and bring Page in at left-back and move Byram to right-back. He should also bring in outstanding young defender Reece Burke in place of makeshift centreback Havard Nordtveit who was another who struggled in Slovenia.
Play players in their natural positions.
Michail Antonio was like a fish out of water at right-back against Domzale last week
Antonio on the right
Continuing that theme West Ham need Antonio's pace, power, skill and guile going forward.
He should therefore revert back to his natural position on the right wing or as part of a front three which will in turn make Bilic's side much more of a threat.
Antonio also puts the hard yards in so Byram will be well covered defensively, something lacking with Sofiane Feghouli out there last week.
Sofiane Feghouli was one of West Ham's better players against Domzale
Feghouli in the Payet role
With Antonio back on the right, summer signing Feghouli - who was one of West Ham's better players against Domzale last time out - should be deployed in that Dimitri Payet role as the number 10 pushed out to the left.
Enner Valencia looks to be on his way out and his performances under Bilic have been poor to say the least.
Algerian star Feghouli's crossing and technical ability make him Bilic's most gifted and dangerous attacker in the absence of Payet and Manuel Lanzini.
He would cause Domzale a lot more trouble operating in that area and being able to cut in and whip his excellent crosses into the penalty box for Andy Carroll.
West Ham's away goal gives them a strong foothold in the game but the onus will be on Bilic's side to attack as they bid to avoid an embarrassing early exit from Europe for the second season running.