Serena Williams walked off the court in Toronto after her semifinal loss to Belinda Bencic at the Rogers Cup with index finger still pointed skyward as she exited past the crowd.

The question is whether she was reminding the crowd that she's still No. 1 - or herself.

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Tennis.com reported that Williams simply played another erratic match - nine of her 21 wins in Grand Slam play this season have been three-set affairs - but the difference last weekend was that she lost.

ESPN reported that the loss is a big warning sign for the world's top-ranked player as she looks to complete the calendar slam when she embarks on the U.S. Open in two weeks.

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"The reality is Williams' upcoming mission is a distraction that weighs heavily on her. She has vowed to not talk about this quest for the gold-standard Grand Slam, but she has talked about it in code ever since she won Wimbledon," ESPN reported.

Both ESPN and tennis.com made reference to Williams' comment after her quarterfinal win over Roberta Vinci, "Maybe I'm a little stressed out. Maybe I need to give myself a hug."

Against Bencic, Williams again sounded as if she was hampered by nerves.

"I can't [bleeping] play anymore, I'm sorry," Serena told her coach, Patrick Mouratoglou, as her famous serve continued to fizzle.

Meaning that despite Bencic's heroics, the U.S. Open still will be all about Williams herself being her biggest threat to complete the calendar slam. While the alarm bells may exist because of Serena's nerves, the issue is something completely within Williams' control.

No one believes Bencic - or any other player - suddenly has become better than Williams.

"Which is why this loss might end up helping her. I won't say it's the best thing that could have happened to Serena, but it will keep her from having to deal with questions about a winning streak at the Open-the calendar-year Slam is quite enough pressure. It will also remind her that any dips in form or concentration really can lead to a defeat. Most important, rather than feeling as if she's always defending her position at No. 1, perhaps this will allow her to have a more attacking, I-have-something-to-prove mindset in the way she approaches the next two tournaments. She can take a breath now," tennis.com surmised.

Whether she exhales won't be determined until U.S. Open time.

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