Serena Williams did not enjoy the comfortable win over her sister Venus in the fourth round too much. However, come Tuesday, there will be no such emotions as the world number one continues her quest for a "Serena Slam" and an eventual calendar slam with a quarterfinal match against former Australian Open winner Victoria Azarenka.
The US Open, Australian Open and French Open champion showed just why she is the best player in the world on Monday, coming up with the big serves when she needed it to get the better of Venus.
"It's hard to feel excited about [beating] someone you root for all the time no matter what and you love so much and is your best friend in the world," Serena said after beating her sister 6-4, 6-3.
"It's never easy but you just play for the competition and enjoy the moment. It definitely doesn't get easier but I was out there and I thought: 'wow, I'm 33 and she's 35 and I don't know how many more moments like this we will have.'"
One player Serena is likely to have a lot more matches with is Azarenka, with the two enjoying a few close matches in the recent past. Azarenka, seeded 23 in this tournament, has gone off the radar a little in the last couple of years because of injury, but there have been signs of late that her old form is on the path of return.
While Serena has not been at her absolute best, it goes without saying that the American will start as the favourite. But Azarenka, who eased past Belinda Bencic in the final 16, has looked good all Wimbledon, and, like Serena, has not dropped a single set on her way to the quarterfinals.
If there is one player capable of giving Serena a real fight it is certainly Azarenka, but the Belarusian will need to be at her absolute best to pick up her first win over the American in a Grand Slam.
"A lot of things that have happened to me in the last two years have taught me a lot of lessons and helped me to grow and mature very quickly," said Azarenka. "As a person and as an athlete I feel different than I was before my injury."
Where to Watch Live
Get the Serena vs Azarenka Report HERE
Serena vs Azarenka is scheduled to begin after the Maria Sharapova vs Coco Vandeweghe quarterfinal, which begins at 5.30 pm IST (1 pm BST, 8 am ET).
Audience watching Wimbledon in the UK can can do so on BBC One and BBC Two, while the matches can also be live streamed on BBC iPlayer.
US viewers can switch to ESPN, with the live stream option on Watch ESPN. Australia viewers can watch Serena Williams play Victoria Azarenka on Channel 7, with the online live streaming option on 7tennis.