Just five competitors have completed the feat in history, with Lindsay Davenport (1997 and 2000) the only individual to do it on more than one occasion.

There are 15 men and 12 women scheduled to compete in both formats and tournament director Tommy Haas hopes the financial reward prompts more of the top players to take part in the doubles.

"We want to encourage more of the top singles players to play doubles at the BNP Paribas Open, and therefore are offering a bonus of $1 million in 2018 as a significant incentive," Haas said.

"While we have traditionally had great participation by singles players competing in doubles, we know how much our fans love to watch doubles at our tournament, and we want to give them the best possible doubles fields over the fortnight."

Roscoe Tanner, Boris Becker, Jim Courier and Vera Zvonareva are the only other players to have triumphed in singles and doubles in the same year at Indian Wells.