Jordan Spieth could replace Rory McIlroy as the world's number one golfer this weekend
Jordan Spieth will replace Rory McIlroy as world number one if he wins the 144th Open Championship and completes the third leg of an unprecedented calendar grand slam.
Spieth's play-off victory in the John Deere Classic on Sunday means he can overtake McIlroy, who has been ruled out of his title defence with an ankle injury, in the rankings by lifting the Claret Jug at St Andrews.
The 21-year-old's decision to compete in Illinois, where he won his first PGA Tour title in 2013, rather than contest the Scottish Open at Gullane or practise on links courses in Britain has been questioned by the likes of former Ryder Cup captain Paul McGinley.
But the Masters and US Open champion had no doubts it was the right decision after defeating veteran Tom Gillis on the second extra hole.
"I really didn't care anyway," Spieth said. "I came here for a reason, and we accomplished that reason, and certainly have some momentum going into next week. This tournament means a lot to me. This is a tournament I truly love.
"I've got plenty in the tank. Leading into the Masters, those couple of weeks right before could have taken a lot out of me with a runner-up finish and then a play-off loss. And we rebounded nicely."
Spieth is a strong favourite for the Open despite only having played one round at the Old Course before the 2011 Walker Cup at Royal Aberdeen, with US Open runner-up Dustin Johnson and Rickie Fowler next in the betting.
Fowler's win at Gullane has lifted him to a career-high fifth in the world rankings and the 26-year-old is now hoping to emulate Phil Mickelson in 2013 by winning the Scottish Open and Open Championship in consecutive weeks.
Former world number one Tiger Woods, who won the Open at St Andrews in 2000 and 2005 and spent the weekend practising at the Old Course, fell from 226th in the rankings to 241st.