"Most frustrating thing about playing my sister is that it's like playing against myself" - Serena Williams on her rivalry with Venus

Serena Williams reckons the most frustrating thing about playing against her sister Venus is that it closely resembles the feeling of playing against herself. Speaking on the latest episode of the Ellen DeGeneres show, the 23-time Grand Slam champion remarked that the elder Williams had the annoying habit of putting balls that would have fazed anyone else back in play.

The former World No. 1 noted that she herself was a "tough" competitor on the tennis court, but it was a trait she shared with her sister.

"To me, the most frustrating thing about playing against my sister is that it's like playing against myself. I am pretty tough and she is pretty tough, so she gets every ball back," Williams said. "Every time I get a great serve, she's [gets it back]. It would be an ace against anyone else but she gets it back."

Serena Williams leads the head-to-head against Venus Williams 19-12

Serena Williams has a 19-12 lead over Venus Williams as of now

Serena Williams and Venus Williams were involved in one of the most fierce rivalries of all time in women's tennis. The younger Williams currently leads their head-to-head 19-12, but at one point, she was trailing 5-1.

Venus Williams won their first three encounters, beating her sister at the Australian Open and Italian Open in 1998, and the Miami Open the following year.

The 23-time Major winner pulled one back at the 1999 WTA Finals, but the 41-year-old won their next two meetings at the 2000 Wimbledon and 2001 US Open.

Serena Williams then won six matches on the trot, five of them coming in Grand Slam finals. Venus managed to take a 10-8 lead over her sister by 2009, following which the 40-year-old embarked on an era of complete dominance.

The former World No. 1 lost only two of the next 13 times they faced each other (2014 Canadian Open and 2018 Indian Wells Open), notching up victories in five Grand Slams along the way.

Interestingly, the younger Williams has the lead in the head-to-head on all four surfaces. On hardcourt, she has a 12-9 lead over her sister, while she is ahead 2-1 on clay and 4-2 on grass. On carpet, the pair played only one match, which was also won by the 23-time Grand Slam champion.

In doubles, Serena and Venus Williams have 22 titles together, but they never played against each other. The duo faced off once in mixed doubles, with Venus Williams and Justin Gimelstob taking down Serena and Luis Lobo in the 1998 Roland Garros final.