All four men were omitted from this morning's fourballs and so would have felt fresh on the opening tee.
Big-hitting Watson created a rousing atmosphere by encouraging the galleries to cheer during his swing and he duly boomed a drive down the fairway.
The Americans took the first thanks to a Simpson birdie and they were soon two up as Lawrie could only bogey the par-three second.
Both pairs made birdie threes on the next before the lead was extended to first three and then four up thanks to American birdies at the fourth and sixth.
The visiting pair couldn't make any inroads and it turned into the Bubba show as the Florida man birdied three in a row to move the advantage to six up.
At the ninth Simpson stiffed his approach to six feet but Hanson responded with a similarly good shot. However, the Swede's putt lipped out before Simpson also missed to keep the deficit at six up.