By Mark Lamport-Stokes
Aug 10 (Reuters) - The return from injury by Rory McIlroy to defend his title at this week's PGA Championship at Whistling Straits gives the year's final major extra spice as Jordan Spieth aims to carve out another slice of golf history.
World number one McIlroy and second-ranked Spieth have between them won four of the last five majors played and, aged just 26 and 22 respectively, they are likely to dominate the game at the highest level for some time to come.
Much of the focus at Whistling Straits will be on the remarkable Spieth, who will be seeking to join fellow Americans Ben Hogan and Tiger Woods as the only players in the modern era to have won three majors in a single year.