DAILY ticket sales for Port Adelaide's Round 20 night blockbuster against top-of-the-ladder Sydney are likely to sell-out following a rush to purchase reserved seats on Tuesday morning.

Less than 250 single reserved seats remained just one hour after the release of public ticket, with general admission sales likely to be the only available options later this week.

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All general admission sales will be subject to capacity.

It will be Sydney's first match against the Port Adelaide at the Adelaide Oval, following the tightly-fought encounter at the SCG earlier this year.

A capacity crowd looks likely and follows sell-out crowds against Adelaide, Geelong and a record-breaking Hawthorn attendance earlier this year.

Port Adelaide's general manager - member services, Matthew Richardson, says the rate of sales is comparable to that which set the South Australian AFL record attendance in Round 10 this year.

"We posted a record crowd of 52,233 against Hawthorn and today's huge uptake is very similar to the response we had for the game," Richardson said.

"It's likely reserved seats will be exhausted later today or tomorrow and then it will be general admission and 3-game membership sales that will  provide game access.

"We have just three home games left this year - starting with Melbourne this Sunday - and with the night blockbusters against Sydney and Carlton in August, it really is the best value-for-money option available.

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"What we can see by these early sales figures is that this will likely be a sell out and subject to capacity, so if our supporters or Sydney fans are hoping to see the game, they will need to get in quick."

Port Adelaide plays Sydney at 7:10pm on Saturday 9 August at the Adelaide Oval.