Last week it was Rhys Priestland's last-gasp penalty that denied Zebre the win and this time it proved to be du Preez's score, and Harry Leonard's boot, ensuring their only RaboDirect PRO12 triumph remains the win over Cardiff Blues earlier this season.
Edinburgh had the first opportunity to open the scoring on eight minutes after they were awarded a penalty from a scrum but Leonard was off target with the penalty.
Zebre responded and Edinburgh needed a covering tackle from full-back Greig Tonks to deny the Italians the first try of the game on ten minutes.
The visitors kept coming however and they scored the first points of the match on 17 minutes when Luciano Orquera nailed a penalty after indiscipline from Edinburgh at the breakdown.
The lead lasted just three minutes however as Edinburgh winger Dougie Fife made a fine break before finding Tonks, who went over for this second try in as many matches in the corner.
Leonard missed the conversion but midway through the first half Edinburgh extended their lead to 10-3 when WP Nel repeated Tonks' feat by scoring his second try in as many weeks, burrowing over from close range.
This time Leonard was on target with the conversion but three minutes later, Zebre were right back in it thanks to Tommaso Iannone, who squeezed through a gap in the Edinburgh defence to dot down.
Orquera couldn't convert but Zebre weren't finished and after attacking Edinburgh out wide, the visitors had the numbers to put winger Leonardo Sarto away in the corner.
And Orquera bisected the posts with his conversion to hand Zebre a 17-12 advantage at the break.
Edinburgh rallied straight away in the second half and won a penalty at the breakdown - duly converted by Leonard to trim the gap to just two.
Zebre hit back however and only some desperate defence from Edinburgh denied the visitors their third try of the evening.
And Edinburgh made them pay on 56 minutes after some sterling work from their forwards sparked a driving maul before the ball found its way to back rower du Preez, who forced his way over the whitewash. Leonard added the extras to give the hosts a 22-17 lead.
Edinburgh grew in confidence and gave themselves a cushion with another penalty on 63 minutes with several Zebre players offside, Leonard again making no mistake from the tee.
Zebre refused to lie down however and three minutes later they found themselves back within touching distance after another Orquera penalty made it 25-20 and with six minutes on the clock, they trailed by just two, the Italian fly-half adding another three-pointer.
Zebre pressed for the win but they could not fashion the chance to add another penalty or drop goal as Edinburgh clung on for the victory.
|Edinburgh Rugby Score Card|
|Cornell du Preez||1||5|
|Zebre Score Card|