It will be the third time in the space of a year that Welsh fans will have been given the chance to watch their heroes train and they turned up in their thousands for the 2010 Autumn Series and 2011 RBS 6 Nations opportunities.
Once again, fans hoping to the likes of James Hook, Gavin Henson and Jamie Roberts put through their training paces, or to check first-hand on the fitness of the returning Shane Williams, Gethin Jenkins and Martyn Williams, will have to log on to www.wru.co.uk/watchwales4free.co.uk to register their interest.
Entry to the Millennium Stadium will be free to everyone and the session will come just four days before Wales' first warm-up fixture against England at Twickenham Stadium.
"We want as many of the Welsh fans as possible to enjoy the World Cup experience with us and the more fans we can get at our training session on 2 August the more it will lift the players and help them believe they can do something special in September," said Gatland.
."We've got some really healthy competition at the moment and I hope we get another large turn-out so the fans can see that for themselves. It's a way of reaching out to the nation and inviting them to get behind the side.
"We had a great turn-out on the last two occasions we threw the gates open and it was really encouraging to see all the young children and families who turned up to enjoy the day.
"It will be an important training session for us ahead of the first of our three World Cup warm-up Tests and will give the fans a taste of the atmosphere which will be in place a week later when England return to the Millennium Stadium for our second game, and when Argentina roll into town on Saturday, 20 August."
There will be some pre-training entertainment provided for the fans hen the Millennium Stadium gates open at approx 2.30pm on 2 August, with the players due to arrive at 3.00pm for their 'watchewales4free' training session.
The full training session will last for about 90 minutes and sections of the audience will be able to meet team members and get autographs and much more besides.
All you have to do to attend for free is register at www.wru.co.uk/watchwales4free and turn up and enjoy the day.