Wednesday concluded pre-season with a 2-1 reverse against Luton at Hillsborough.
The Hatters had to come from behind as the Owls made the ideal start inside nine minutes after Callum Paterson was tripped in the box by Marvelous Nakamba.
The referee pointed to the spot and Michael Smith duly converted.
The lead was promptly wiped out five minutes later. Pelly Mpanzu advanced into the area on the angle and struck a low drive that whistled into the far corner.
The remainder of the first half was an even affair until Wednesday almost restored the advantage just before the break.
Smith picked out new boy Juan Delgado with a sweeping crossfield ball but James Shea dashed off his line to deny the Spaniard a debut goal.
The Hatters had a better chance just moments into the second half. A swift counter saw the ball land nicely at the feet of Luke Berry 12 yards out but the substitute missed the target from his first touch.
Berry then had a second opportunity moments later after wriggling free of two challenges in the penalty area. The shot was better executed this time but whistled the wrong side of the post.
It was Luton who had the final word, though, scoring the winner seven minutes from time.
Elijah Adebayo delivered a piercing ball right across the danger zone, leaving Carlton Morris the simple task of stroking home from close range.
Wednesday: Dawson, Paterson (Palmer 76), Iorfa, Ihiekwe (Adetoro 79), Famewo, Vaulks (Shipston 76), Bannan (Glover 74), Delgado (Johnson 46), Byers (Bakinson 62), Windass (Wilks 70), Smith (Fletcher 70)