Serena Williams of the USA (left) hugs sister Venus Williams of the USA after their match at the 2015 US Open tennis tournament.

AFP/New York City

Serena Williams and her family want winning the first calendar Grand Slam since 1988 to be a huge achievement if Serena does it, but not so big a deal if she fails.
The 33-year-old world number one took a major step toward the rare feat Tuesday with a 6-2, 1-6, 6-3 triumph over older sister Venus to reach the US Open semi-finals.
“It is important to me, but at the same time, it is what it is,” Serena said of her quest to complete the calendar Slam. “I’ll do what I can.”
Venus said that while Serena has been downplaying the calendar Slam, she and the Williams family see it as potentially the crowning achievement on their legend of coming from a poor neighbourhood near Los Angeles to global tennis stardom.
“That would be huge, not just for me, but for my family just for what it represents and how hard we have worked and where we come from, so it would be a moment for our family,” Venus said.
“But at the same time, if it doesn’t happen it’s not going to make or break you. We don’t have anything to prove.”
Venus, two years older than Serena at 35, picked up her long-time role of protecting her sister.
“She has nothing to prove. She’s really the best ever,” Venus said. “So what are you going to do? Just try to make it. If you don’t, then that’s that and go to the next one.”
Serena, who already holds all four major titles, was surprised to hear about the interest her family has in seeing her complete the calendar Slam after she finished off the second “Serena Slam” of her career at Wimbledon.
“My success is our success. We all started together and we all are still together,” Serena said. “I didn’t know it was important to my family, actually. “
Venus said that calendar Slam backdrop, and the fact Serena could match Steffi Graf’s Open Era record of 22 singles titles as well by winning the US Open final Saturday, made their quarter-final matchup a bit more special than any of their 26 prior meetings in tour-level play.
“It was more unique, definitely, because Serena is going for the Grand Slam and I think everybody is interested because she has to play her sister to get to that,” Venus said.  
“People want to see how that’s going to come out. So it was definitely a different moment.
“It definitely was intriguing.”
Celebrities were among the 23,771 filling Arthur Ashe Stadium, pondering Venus to be asked what the late Ashe might have thought.
“I imagine he would enjoy the moment,” she said.
Serena ignored the hype over the calendar Slam, going into hermit mode.
“I didn’t really listen to a lot of the press and read anything about it,” Serena said. “I kind of was in a hole and I didn’t turn on my TV and didn’t watch any of the matches yesterday, men or women. I didn’t really live in that world.”
She called the most satisfying moment of her match against Venus “walking off the court and it being over with.”