Swansea's new football and rugby stadium will be just over half full for its opening game to comply with health and safety rules.
There will be a 12,000 capacity for the first game
The crowd capacity at the 20,000 all seater arena has been set at 12,000 for Swansea City's pre-season friendly with Premiership side Fulham.
Officials expect the game on 23 July to be a sell-out.
A second friendly against Blackburn is also likely have the same restrictions.
Season ticket holders will be given a priority for both games.
But the club stressed the ground would be operating at full capacity for the kick-off of the Division One season at the start of next month.
Project director Steve Evans said: "This is going to be one of the most memorable sporting occasions in the history of the club.
"However, because of football licensing regulations put in place following the Taylor report, and as these are the first events at the new stadium, we will be reducing the capacity for the Fulham match, and possibly the Blackburn game."
The Swans have sold more than 7,000 season tickets, who will be given priority booking from Thursday for the two friendlies.
Any remaining tickets will then go on general sale.
Mr Evans added: "We are expecting a massive demand for tickets, so I do need to stress that both matches will be all-ticket and that there will be no tickets available on the day of either game."
The Swans, who kick off their league season at home to Tranmere Rovers on 6 August, will share the new ground with the Ospreys regional rugby side.
The Ospreys are set to make their first appearance at the £27m stadium at Llandore against London Wasps on 26 August.