Last week, defending Wimbledon champion Marketa Vondrousova slipped badly in a grass tournament in Berlin and could not continue her match. The diagnosis? A hip capsule injury and uncertainty about whether she will be ready for Wimbledon. But she is far from the only player who has been forced to abandon a match or pull out of the tournament.

Felix Auger-Aliassime didn't finish because of his hip, Andy Murray and Anna Kalinskaya gave up due to back pain in their matches, Aryna Sabalenka didn't play because of her shoulder, Anastasia Potapova withdrew due to knee problems and Daniel Evans pulled out due to knee pain.

But the list is far from definitive, with over 20 names in total. It also includes Katerina Siniakova, who did not want to risk aggravating the injury to her right leg, which she suffered when she slipped at the same tournament as Vondrousova.

And finally, also Karolina Muchova, who has played less than two matches after a break of almost 10 months, preferred to take another break.

When withdrawing from tournaments, the head often plays a big role. Some are haunted by fears of pain or a longer period out. After all, the tennis season is extremely demanding and there are few opportunities for a few days off. At the same time, the transition to a grass surface is very problematic for a tired body. Another factor is that tennis players play with different balls almost every week, which again increases the risk of injury rapidly.

Grass is not for everyone

Grass is erratic and the least kind to the body. It is fast and slippery and the balls bounce low. Tennis players must have a very low centre of gravity, react skillfully to irregular bounces and, last but not least, move differently.

I have experienced the treachery of this surface firsthand. On one slip, I put my foot down, heard a crunch, and immediately knew something was wrong with my hip. I had heard from the people around me that the grass was perfect for my game. That I was left-handed, that I played fast. I didn't move all that badly, but the fear of the surface, caused by the hip injury and later by a tweaked knee, when the leg stuttered when running on a small bump, was reflected in my movement on the court and I could say goodbye to good results on grass.

Of course, it depends on the individual. Some people fall on grass very often, others can stand anything. As soon as Petra Kvitova stepped on the grass court, she was like a fish in water and excelled. Iga Swiatek, on the other hand, avoids grass. She hasn't played a single tournament on it this year in preparation, resting and focusing on the Grand Slam itself. She might not want to risk injury either.

But she shouldn't underestimate herself because she is a junior Wimbledon champion. But her zero matches on grass this year may limit her.

Is Muchova's comeback too soon?

Karolina Muchova's game is perfect for the grass surface, she knows how to move on it. I like the way she is always good at getting her feet where she needs them to be so that she has stability and is well-positioned on her shots. Also, she is extremely skilled and has an impressive feel for the ball. She is one of the few players who goes to the net and that works on grass.

Her comeback this week at Eastbourne after almost a year off was a success. But she sadly missed the quarter-final match due to injury. I dare say that injury-induced breaks wreak havoc on the psyche and I wouldn't be surprised if worries about another setback creep into her mind. The rankings can be frozen in the event of injury, but only for a certain amount of time, so players are often forced to return earlier than would be ideal.

In terms of skill, Muchova can safely compete with Vondrousova. For her, it is a question of how she will "shake off" the fall from Berlin. But Marketa has excellent character, she never worries about anything.

Moreover, she is the type of player who doesn't need to have played dozens of hours before the tournament. She makes up for it with her skill and mindset. She's experienced in coming back from injury. Mental well-being will be important for her.

This year, she will enter the tournament with a tattoo that reminds her of last year's triumph. And since the winning line-up is unchanged, her sister and mother, besides her coach Honza Hernych, will make her feel comfortable at Wimbledon.