A late signing in the recent transfer window, Light last played in Victoria, Australia, but is now resident in Christchurch, and travels south with United's other imports.
Malcolm Fleming gave Light an hour before bringing on James Reichwin.
Not a bad start, considering he was playing on the left, and prefers the right side.
But he finished well, said the coach.
Yet, it was Wellington that made the early running, hitting crisp passes and scoring after only three minutes, when Chris Davies took advantage of some slack defending to shoot past keeper James Waggett.
At that stage, Wellington lived up to recent plaudits and a winning form that has lifted the side up the NZFC table.
But Otago dug in, and after some desperate defending, regained composure, and started to win the midfield battle.
Robbie Deeley and Andy Coburn harried the Wellington side into mistakes, with Ryan Faichnie and Light working hard across the field, closing down passing options.
Davies might have put Wellington further ahead but his close range header went over Otago's crossbar.
The home side started to create incisive attacks that pushed the visitors back.
Light scored after sustained Otago pressure had Wellington struggling to clear, and it was Deeley who slipped the ball to Otago's new signing in the 31st minute to equalise.
Tails up, Otago played its best football, with steady ball possession that had Stu Kelly set up Dave Dugdale for a superb shoulder-high volley that flashed past keeper James Bannatyne on the stroke of half-time.
Again, Wellington started well in the second spell, testing the resolution of United captain Tim Horner and centreback Tom Sadd, and fullbacks Tristan Prattley and Rhys Henderson, who had replaced Mike Abbott.
Keeper Waggett also showed top form with a brave block as Davies raced through, but Wellington ran out of ideas and Otago gained ascendancy.
The midfield screen forced Wellington into harmless square passing, while Otago carved out opportunities that climaxed in a well-worked goal.
Faichnie left defenders in his wake during a trademark dribble, then delivered a cross which Wellington struggled to clear and Light darted in to ram Otago into an impressive 3-1 lead.
The question was whether Otago could maintain its high energy pressure game to deny Wellington, its attacks eventually being snuffed out as the home side played composed football.
Dan Ede came on for Otago and carved through opposition ranks, James Reichwin gave a positive point of attack and, in the closing stages, the home side looked comfortably in charge.
Horner said: "Apart from that early pressure, I felt we were rarely tested in front of goal, and once we got our second wind I felt comfortable."
Clearly disappointed, Wellington assistant coach Charlie Howe agreed that Otago was well worth the three points.
In what has become a tight competition, Otago is now in third position, four points behind Auckland and Waitakere, and four ahead of a pack of five teams, which is covered by only four points.
