Roberto Castro cashes in with a first round of -5 under par 66 in the AT&T National at Congressional Country Club. Roberto Castro / Getty Images Roberto has made a habit of starting fast in tournaments this season, he has carded 66 or lower in the opening round of a PGA TOUR event four times, including Thursday at the AT&T National, where his 66 was good enough for a two-shot lead, on the par 71 course. He spoke about the other times this season he has been at the top of the leaderboard, and how tough this course is; " They were totally different rounds, the one at Sawgrass, I hit it three feet eight or nine times. The one today was more of a normal lower round where I made some putts. The rough's brutal, we probably were 50 percent you'd get it up to the green and 50 percent pitching out. It's very similar to a U.S. Open in that there's not a lot of birdies out there. You're just plugging along. Golf course hasn't changed much in two years." There are a trio of players who are just two shots back on -3 under par, the in form Billy Horschel, Bud Cauley and Graham DeLaet. Billy also compared the lay-out of Congressional to that of Merion in the US Open, with regard to the toughness just off the fairway; " It's like another U.S. Open, off the fairways, the rough is thick. Tough to hit the ball on the green. Fortunately, the greens are soft, so they're really receptive. It's still a tough golf course. Got to drive the ball really well here, give yourself opportunities. This year, I've worked hard on my short game and my putting. When I do miss one offline, I can get it up and down on a regular basis. The tougher the golf course, the better I play. Those U.S. Opens usually, and I won earlier at Zurich this year, which was a big confidence boost. My first major as a pro, I finished fourth with a really good field and had a chance to win going into the weekend, you can only build confidence in that." Billy Horschel / Getty Images These guys are followed by a group of eight players, who together are another shot back on -2 under par.