World number one Luke Donald faces a tournament dilemma as he aims to become the first player to top the money lists in both the US and Europe.
The 33-year-old Englishman is teeing off in the Dunhill Links championship which takes place at different courses in Scotland on Thursday.
Donald has stated that he intends not to partake in the four remaining US events but may change these plans if Simpson overtakes him.
"Right now I'm not planning on playing another event [on the PGA Tour] but I have to weigh up the pros and cons of trying to win the money list, for personal reasons and in terms of needing rest," Donald said.
"I'm not sure whether [Simpson is] playing an event either but he might be and then I'll be tempted to add one too."
In addition to this scheduling issue, Donald's wife Diane is expecting their second child in six weeks.