If you haven't heard, the tour seeding and performance validation process for the new prototype Titleist 913 drivers is now under way.

It began early yesterday morning on the range at the AT&T National with the sound of Titleist Brand Ambassador Bobby Gates hitting a new prototype Titleist 913 driver for the the first time, his Pro V1x golf ball launching far down the range at Congressional Country Club.

Several other Titleist players, including S.Y. Noh, Jimmy Walker and Brendan Steele, also took their first swings with the new prototype 913 drivers Monday, our Titleist Tour Reps there to help them get dialed-in with their optimal shaft and SureFit Tour hosel setting.

Meanwhile, Titleist Brand Ambassador Rory McIlroy took advantage of a nice day in Ireland to test his new prototype 913 driver with Titleist Tour Tech Mattias Jelver before getting ready to play in this week's Irish Open.

The buzz will get even louder Tuesday, as many more Titleist players arrive at Congressional, each with a new prototype 913 driver built to their specifications waiting for them in the Titleist Tour Van.

Take a look at Team Titleist's pictures from Monday's testing sessions in the slideshow below, and stay tuned for more pics, video and updates from Congressional.