Sandaza then had the net bulging only for the effort to be disallowed after Feeney was deemed to have fouled goalkeeper Jamie Langfield in the build-up to the strike.
United are closing in on another appearance in the Co-operative Insurance Cup final after Scott Robertson's first-half goal eased them past Dunfermline 1-0 in their last-eight tie at Tannadice.
A brace in the last five minutes gave Dundee United a 2-0 victory they desperately wanted in their first game since the death of chairman Eddie Thompson.