World number nine Elina Svitolina, who has won 13 singles titles on the WTA Tour, will be writing columns for the BBC Sport website during the French Open, which runs from 26 May to 9 June.

The Ukrainian, seeded ninth, is hoping for a successful run in Paris, having become known as one of the WTA's leading players on clay, twice reaching the quarter-finals at Roland Garros.

The 24-year-old, who was at a career-high ranking of three last year, has struggled with a knee injury in recent months, but earned her first win of the clay-court season by beating seven-time Grand Slam champion Venus Williams 6-4 6-4 in the opening round.

Beating Venus Williams in straight sets was a good sign that I'm mentally strong enough to overcome the challenges I've been facing this year.

Playing one of the all-time greats in the first round after losing my past four matches was mentally very tough and my main emotion after winning was happiness.

But after my injury troubles, and not winning a match in Madrid or Rome, I was also relieved to get the victory.

On the one hand, it can be good to have a tough opponent like Venus at the beginning of the draw because it puts you straight into 'tournament mode'.

But on the other hand it is also a little draining. Your mind has to be sharper than perhaps it usually has to be in the opening round.

Against such a great champion, I had to step up my game, be focused from the very beginning and take my chances.

As I said before the tournament, I don't have any expectations about how far I can go at Roland Garros, so now I just want to be ready for the second round and compete well.

I'm happy I haven't lost my confidence with that run of losses - when things aren't going well it has to be part of your personality and mindset as a tennis player that you don't lose confidence.

But I was pleased to have two days off before I play in the second round on Wednesday. Now I have time to recover mentally.

'The small details matter when fighting injury'

As well as resting mentally, the two days off will be important for my knee's recovery. I didn't feel any pain on Sunday but we try to take one day at a time.

The small details really matter, especially with injury when you are playing such a big event - with this level of pressure, you can snap any time.

We will do recovery and treatments - we have a machine that has the same effect on an injury as an ice bath or cryotherapy but that uses oxygen. It looks like a spray but is actually oxygen with ice effect.

So you 'spray' this to the place it hurts and the body reacts like it is a burn. So the blood starts to move quickly and the recovery speeds up.

This type of stuff, along with lots of massage and exercises to strengthen the muscles around the knee, is very important for recovery.

I will watch my boyfriend Gael Monfils' match on Tuesday, of course - then I will be ready and fresh for Wednesday.

'Important to share your off-court life with fans'

As well as our Instagram account, Gael and I had plans for a behind-the-scenes documentary.

I think it's important to share your lives with fans, and there aren't many documentaries made about life off the court. I think it will help aspiring tennis players growing up to see what they will have to deal with in the future.

People see what's going on when you're playing a match but don't see what's going on behind the scenes, not only in the good moments but also the tough ones.

Anyway, we did a little bit of filming but then had to stop because there were issues about access at some tournaments. The prices for filming were super high - we would have spent almost all our prize money on it!

So we've stopped filming for a while and we will see how it goes - maybe we'll keep the footage and try to start the documentary again in the future.

Playing childhood friend at a Slam is 'amazing'

On Wednesday I will play Kateryna Kozlova, another Ukrainian, in the second round.

I've known Kateryna since we were about eight. She was born in a city close to my own, and is only seven months older than me, so we grew up playing against each other in junior tournaments.

We were very good friends and just having fun - that's all it was about at that age. We didn't really talk too much about the future.

We have played each other many, many times but never on the WTA Tour so it's amazing we're now here in a Grand Slam facing each other.

But although we are still friends, and talk a little bit from time to time, I have my team around me and she has her team so it is very tough to connect all the time.

It is very rare to maintain strong friendships on tour like normal girls. I mean, I speak with all the girls and we're very friendly, but is tough to keep the same relationship with friends as you had before because you are all so busy travelling and competing.

But it is great to be playing an old friend - and it is great for Ukrainian tennis to know there will definitely be someone from Ukraine in the third round!

Elina Svitolina was speaking to BBC Sport's Jonathan Jurejko at Roland Garros.