Third seed Karolina Pliskova is among the favourites to win the women's singles at the US Open but faces a tough test against Britain's Johanna Konta in the last 16.
In her latest BBC Sport column, the Czech reveals why she is keen to hit as many as aces as possible in a Grand Slam tournament - and not only to help herself.
Serving is my biggest strength so when I play Johanna Konta for a place in the quarter-finals I want to hit as many aces as possible - for two reasons.
Of course, the first is to help me win the match! The second is because I am giving $200 (£165) to charity for every ace I hit here at the US Open.
I started donating in this way two or three years ago and it has been very successful in raising money because I'm always sure I can hit a lot of aces every match. Well, normally I do, but not always!
In my first-round match I only hit four so I was thinking I needed to hit more. Then I managed nine in my second-round match and 10 in my last match so it is getting much better.
I donate $100 for every ace I hit at every Grand Slam and a local company in the Czech Republic then matches it with $100.
The total is then donated to a good cause in the Czech Republic and we decide where it will go after the tournament.
So far this has included hospitals with paediatric oncology departments, direct donations to children diagnosed with cancer, and helping provide housing and wheelchairs for elderly people.
The money has also helped fund tennis tournaments in Czech Republic and a kids' camp which I put on in Prague in the summer.
Giving something back to people back home is something which means a lot to me. I know I'm lucky to have the opportunities to give money and also ask people who can also help.
Everybody feels different about this but I feel better when I can help the people who need it.
That provides motivation because the more aces I hit the more chance I've got of winning the match - and it helps everybody!
'I knew Johanna when she was Australian!'
Playing Johanna will be a big test for me because she has a good record at the Grand Slams, having reached the French Open semi-final and the Wimbledon quarter-finals this year, and is always close to reaching the final.
She has had a great year, as she did in 2017, although she had a tough one last year. She can be a little bit up and down but of course she is a dangerous player.
Johanna has a lot of weapons, a good serve, good groundstrokes, and is playing with more variety here. So it will be very difficult.
Ons Jabeur, who I played in the third round, is a player who mixes things up a lot, playing a lot of drop-shots and slices, but I think with Johanna it will be more about baseline hitting.
I think it is better to play someone who plays with less variation and, although Johanna can hit a lot of big winners, I prefer to play that style because at least it is cleaner tennis.
We have played a lot of times and I'm aware I have a good record against her, including having beaten her in the Italian Open final in May.
It is something I'm aware of, of course, because I still have those matches in my mind, how we played and how I beat her.
But every match starts 0-0 and I won't be thinking too much about the past because that is when you can start losing quickly.
Of course Johanna also believes every time she is going to win so I have to be ready.
I don't know her personally, we haven't really hung out together. But we have been on the tour for a long time - I knew her when she was Australian before she changed to be British!
We even played each other in an ITF 25k back in 2011 - so I have known her for a very long time and we have both come a long way since then.
Johanna is a nice girl, friendly and always plays fair on the court.
For me it will be about focusing on my serve because maybe it is better than Johanna's.
I have hit 23 aces so far in the tournament but my serve has still not been at its best.
I know I can hit more aces and that comes when I'm relaxed, hitting clean without much energy and just swinging. I hope it will be like that on Sunday - and then everyone will be happy.
Karolina Pliskova was talking to BBC Sport's Jonathan Jurejko at Flushing Meadows