Is Serena Williams' Poor Hopman Cup Performance a Sign of Decline?

Two years after becoming the oldest woman to hold down the No. 1 ranking, Serena Williams remains on a "decline watch."

Dominant for nearly a decade, Williams often plays a stratosphere above the rest of the women on the WTA Tour. So when her game crashes back to earth, the decline watchers wonder: could this be the beginning of the end?

Williams' recent performance at the 2015 Hopman Cup may be the first sign of serious decline.

Williams, 33, lost two of the four singles matches at the mixed-doubles tournament. Remember in 2013, Williams only lost four matches the entire year.

Despite reaching the final with John Isner, Williams suffered a disastrous Hopman Cup appearance. 

She lost to Agnieszka Radwanska in the finals. Eugenie Bouchard defeated Williams 6-2, 6-1. Williams needed three sets and two tie-breakers to beat Lucie Safarova. She also needed three sets to defeat Flavia Pennetta. 

What do Bouchard, Safarova and Radwanska have in common? Up until Hopman Cup, none of them had ever beaten Williams. Pennetta's only victory against Williams is a walkover. 

Williams went the entire 2014 U.S Open without dropping a set. At the Hopman Cup, she lost six sets in four matches. 

Theron Kirkman/Associated Press

Worse, Williams looked awful. Although the Hopman Cup is a glorified exhibition, it's hard to ignore how poorly she played. It wasn't a few lulls during matches. Williams looked lethargic and out of sorts for most of the tournament.

She caused a stir by ordering an espresso during her match with Pennetta, as noted by The Associated Press. She complained of extreme fatigue. 

Williams, 33, turns 34 in September. Over the last year she's shown signs of slowing down. 

The first sign of fatigue came during the WTA Championships final in Singapore. Simona Halep, who had never defeated Williams, crushed the No. 1 player 6-0, 6-2. It was one of the worst losses in Williams' career. She avenged the loss in the final, but it was a wake-up call. 

Williams went on to play in the International Premier Tennis League during what would normally be her time off. She traveled from Manila to Singapore, then back to Florida for a charity run before heading to Perth, Australia. 

Perhaps it's merely excessive jet leg. Whatever it is, it's impacting Williams' game. 

After her loss to Bouchard, Williams talked with ESPN about lingering fatigue. "I don't know what's wrong with me, I'm so tired...I can't get my body to move. I feel like I've got no energy."

Might this be more than a mere momentary malaise? 

Tennis great Chris Evert often talks about how difficult life on tour becomes for players over 30. She points out that the bad days are more frequent and you have no idea when you're going to have them.

In 2012, when Williams, then 30, was upset at the Australian Open, Evert told the Mirror," Maybe that now she is 30 she is having more bad days, more flat days. Some days you don't want to get out of bed in the morning. It was all about motivation."

Last season, Williams had what she considered a bad year. After going 78-4 in 2013, winning the French Open, U.S. Open and a record $12 million-plus, Williams went 52-8 in 2014. She won the U.S. Open and just over $9 million. Considering no other player on the tour did better, Williams' off year would be a dream season for most.

Williams may face more off days and upsets this year. However, if last season is any indicator, she will have far more good days. On those days, she'll soar above the competition and be her usual spectacular self.