Port Adelaide was left wondering, 'If only' after going down by just three points in atrocious conditions in a sensational NAB Cup quarter-final overtime thriller against Geelong in Darwin on Saturday night.Rain tumbled relentlessly in sheets throughout the contest at TIO Stadium leaving the ground thoroughly waterlogged and the ball like the proverbial cake of soap.But the pragmatic Cats, riding their luck, managed to prevail - 0.9.6 (60) to 0.7.15 (57).Scores were locked at 54-apiece at full-time and the Power had by far the better chances to seize victory in the five minutes each-way which followed.But Brett Ebert missed two gilt-edged opportunities and Chad Cornes hit the post from 15 metres out with a set shot that would have won the match for Port with 30 seconds remaining.In the end, it was Cameron Mooney's extra time goal, his fourth for the match, which proved the difference.Despite kicking into a stiff breeze, Port dominated the opening term, racking up a collective 105 possessions for the period to Geelong's 54 which translated into a 17-point break on the scoreboard.The Cornes brothers were right at home in the conditions along with former Tiger David Rodan, while key forward Damon White displayed outstanding mobility and deft handling for such a big man to gather 10 possessions and a goal for the term.With the wind, Port may have expected to bust the game open in the second term, but the Cats lifted, managing to keep the Power goalless in that period and scoreless in the third while slotting through six goals of their own including two to the elusive Shannon Byrnes and two to Mooney.Wet-weather specialists Jimmy Bartel and Corey Enright were providing the Cats with plenty of drive, while highly-rated first-year midfielder Joel Selwood was hard and committed at the stoppages.The Cats looked just about home when Territory local, Nathan Djerrkura gathered brilliantly to run into an open goal for a score late in the third quarter which put the Cats 17 points to the good.But after being anonymous bystanders for two quarters, the Power rediscovered their 'A-Game' in the final term.First-year forward Adam Cockshell announced himself with two goals, and White slotted another as Port drew six points clear with four minutes left on the clock.Two minutes from time Bartel pounced on a loose clearance for a super snap that levelled-up the scores. Extra time seemed a big ask of two teams that had run themselves ragged all night, but the Cats managed to hang on.PORT ADELAIDE: 0.4.1, 0.4.6, 0.4.6, 7.15 (57)GEELONG: 0.1.2, 0.4.4, 0.7.6, 0.9.6 (60)NINE POINT GOALS: Port Adelaide: NilGeelong: NilSIX POINT GOALS: Port Adelaide: White 2, Cockshell 2, Gray, Burgoyne, LadeGeelong: Mooney 4, Reynolds 2, Byrnes, Djerrkura, BartelBEST: Port Adelaide: K.Cornes, White, S.Burgoyne, Rodan, WilsonGeelong: Bartel, Mooney, Enright, Byrnes, Scarlett, SelwoodINJURIES: Port Adelaide: NilGeelong: NilREPORTS: Mathew Stokes (Geelong) for rough play on Dom Cassisi (Port Adelaide) in the third quarterUMPIRES: McBurney, Kamolins, Ryan, NichollsCROWD: 4,804 at TIO Stadium