The maths of the clay surface are distinctly different to grass or hard-court surfaces.

CNN: Tennis interactive: Why clay is so different

When he returns he will be on his favourite hard court surfaces and he understands what he needs to do.

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The 27-year-old, who injured his left knee last October, is hoping to avoid more knee problems by cutting down on the number of times he changes court surfaces.

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Like many tennis players, she prepares for competing on different surfaces hard court, clay and grass.

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Some of the bruises indicated "heavy impacts" with "solid surfaces or objects", the court heard.

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The crushed-brick mixture that constitutes the base of a clay court produces a the highest bounce and most friction of the three surfaces, meaning they have the lowest CPR of all three surface types and are considered as the "slowest".

CNN: Tennis interactive: Why clay is so different