Has Serena's partying led to 'icy rift' with sister Venus?

World number one Serena Williams' partying has reportedly caused an icy rift between her and her sister Venus Williams, according to rumours from tennis insiders.

The American tennis champs have not been seen together off the court in recent weeks, and many wonder if Serena's late nights out and disappointing doubles performances have annoyed the more low-key Venus.

An insider was heard during the US Open claiming that Serena and Venus are not in a good place right now, adding that the later is angry with the world number one because of her active social life off the court, New York Post reported.

Some even noticed that Venus and Serena didn't arrive together or even speak to each other at the Taste of Tennis kickoff event for the US Open a few weeks ago. Another insider said that there was no acknowledgment that either one was even there.

Nor have the sisters been visible on one another's Instagram feeds, with the last picture of Venus on Serena's feed being three months old, while the world number one appeared on Venus' feed two months ago.

On Tuesday, there was reportedly no sign of Venus at Serena's presentation of her HSN clothing line at the Style360 lounge during Fashion Week.

The sisters lost in the US Open women's doubles quarterfinals after they had to pull out at Wimbledon, where Serena developed a mysterious illness. They'd also declined to appear together at a mandatory press conference after losing at the US Open.

Venus' rep, Lisa Sorensen, revealed that she was not with Serena after the US Open because she went directly to Canada to prepare for the Quebec City WTA Open.

Sorensen denied any rift, saying that she is very surprised by these accusations, adding that they are completely false. She said Venus and Serena always have been and continue to be close and supportive of one another.

Meanwhile, Serena's rep, Kelly Bush Novak, also denied any bad blood between the sisters, and called the story an absolute lie and reckless. She said that the sisters continue to be each other's biggest fans and a beacon of support for each other.

Novak said that there is no change in Serena and Venus' very close and special relationship.