Britain's newest battleship had been due to sail out of the Scotstoun yard on the Clyde last Friday, but her voyage was delayed because of a fault in the ventilation system.
Just hours before the £1billion warship was to leave, engineers discovered a faulty valve in a high-pressure air system which links in to its ventilation set-up, and her departure was halted until repairs were carried out.
Officials at the BAE Systems yard said the ship would leave Scotstoun at 2.30pm today.
But the delay means the last of a fleet of six Type 45 warships built at Scotstoun and Govan will not arrive in Portsmouth tomorrow as originally scheduled.
HMS Duncan was to be officially handed over to the Ministry of Defence at a ceremony commissioning her into the Royal Navy tomorrow.
It's thought she will now not reach the military port until Saturday when she will join the other five Type 45s.
The new fleet, built at a cost of £6bn to replace the ageing Type 42s, is the most advanced of its kind in the world.