In 2014, Serena Williams became just the fifth player in WTA history - and the first since Steffi Graf in 1996 - to achieve this feat. What is it? Keep reading to find out...
WTA Staff

PALM BEACH GARDENS, FL, USA - There's no doubt about it, Serena Williams has been becoming more and more of a WTA legend over the last few years, joining some of the all-time greats on all kinds of all-time lists. A lot of that has to do with her week-to-week consistency - while she always had the game to win the big ones, lately she's been coming through time and time again at regular events.

That consistency throughout the 2014 season has brought her yet another rare accomplishment:

Serena is just the fifth player in WTA history to hold World No.1 for a whole calendar year.

Here are all the players who have achieved the feat:
Chris Evert (1977, 1981)
Martina Navratilova (1983, 1984, 1986)
Steffi Graf (1988, 1989, 1990, 1994, 1996)
Monica Seles (1992)
Serena Williams (2014)

Williams is the first player to achieve the feat since Graf did it in 1996, and since Graf was actually co-World No.1 with Seles for most of 1996 (all but seven weeks of the year), Williams is the first player to hold the World No.1 ranking for a whole calendar year all on her own since Graf did it in 1994.

This year the 18-time Grand Slam winner was asked about her recent stranglehold on the top spot.

"That's why I try so hard in the other tournaments, is to have an opportunity to be No.1," she said.

"Obviously I want to win the Slams, but I always like being the best. The past several years, the effort I've been making outside of the Slams and everything, it kind of speaks to that."

And it doesn't sound like she's going to slow down anytime soon.

"I love tennis and I love the sport," Williams commented. "Especially lately, I've been having so much fun competing, when normal people have retired and gone on with their lives. But I've just been having such a great time winning titles and chasing different goals that I have personally.

"I've been enjoying every minute of it."

Back to holding World No.1 for a whole calendar year, one other player came ridiculously close to adding her name to the list - Caroline Wozniacki. Wozniacki was World No.1 for all but one week of the 2011 season - the week of February 14, Valentine's Day week, when Kim Clijsters took over for just that week. It wasn't such a stretch, really - Clijsters had won the last two Grand Slams.