Mahan beat compatriot, Matt Kuchar 6 & 5 while Wilson beat the challenges of Sweden Peter Hanson, won 4 & 3.
"For the most part I felt I played pretty well," said U.S. Open champion. Westwood also won the game at 16 but he was given the green earlier fears after Laird won the first hole.
"He started to how I want to start," Westwood conceded. "He could have three after three, but he gave some [holes] around the bend and you can not do that at this level."
Laird bogeyed the sixth, seventh, ninth and the tenth to reward excellence Westwood three shots and, although the British handed back after three-putting the hole 11, a three-shot lead was restored when the other three for Scotland out of a bunker on the 14th.
McIlroy added: "This is definitely what I want and I think this is the game everyone wants to see.
"I knew I had to play my best. This will be a big day, but I can not get too far ahead of myself I was just concentrating on beating Lee Westwood and it's difficult enough task in itself ..
