His side's fifth consecutive victory lifted them five points clear of their nearest challengers and to within hailing distance of third-placed Chelsea, but O'Leary resists the temptation to set his sights on a Champions' League place.
"I'll settle for fourth place with this team," he said. "I don't think it is possible for us to go higher because we don't have the depth of squad to match any of the current top three. I have nobody to bring on when our key players get suspended.
"They are in their own little league, and if we finish fourth we will have won the other league. My players are already over-achieving for me."
On that reckoning, Wednesday must be two or three leagues further down the pecking order, because a single enforced absence is enough to set the alarm bells ringing for them, such has been their reliance on a couple of charismatic individuals this season.
The Paolo di Canio saga may be behind them, but such is their dearth of goal scoring talent that the suspension of his fellow Italian Benito Carbone was enough to make this Yorkshire derby a one-horse race even before it began.
Their manager, Danny Wilson, admitted that his side never looked like scoring and confirmed that his season-long search for a reliable striker goes on. Wednesday pretty well matched Leeds in their approach work and chances created, but with Andy Booth and Ritchie Humphreys firing nothing but blanks, Nigel Martyn's goal never came under serious threat.
What Leeds possessed and Wednesday did not was an appetite for goals, and nobody was hungrier than Jimmy Floyd Hasselbaink. He put Leeds ahead with a well-worked free- kick after only four minutes, sent another fierce 25-yard drive narrowly wide, and would have scored from the same range with the last kick of the match but for Pavel Srnicek's flying save.
Though his teenage striker partner Alan Smith worked hard, he never found his finishing touch, and it was left to midfielder David Hopkin to complete the Leeds victory at the second attempt after Srnicek had blocked his first shot.
Not yet vintage Leeds, but O'Leary's blend of youth and experience continues to mature nicely, and it cannot be long before even he is willing to place the Premier Cru appellation on them.
Goals: Hasselbaink (4) 0-1; Hopkin (72) 0-2.
Sheffield Wednesday (4-4-2): Srnicek; Atherton, Thome, Walker, Hinchcliffe; Sonner (Briscoe, 32), Rudi, Jonk, Alexandersson; Booth, Humphreys (Agogo, 49).
Substitutes not used: Newsome, Stefanovic, Pressman (gk).
Leeds United (4-4-2): Martyn; Haaland, Woodgate, Radebe (Wetherall, 85), Harte; Bowyer, Batty, Hopkin, Kewell (Korsten, 87); Hasselbaink, Smith. Substitutes not used: McPhail, Jones, Robinson (gk).
Referee: G Poll (Tring).
Bookings: Wednesday: Atherton, Thome, Booth, Agogo, Hinchcliffe.
Man of the match: Hasselbaink.
Attendance: 28,142.Reuse content