Possible Clues:

• Mitochondrion-made material, briefly
• Org. for Roger Federer
• Sports org. for Nadal and Djokovic
• Org. with a racket in its logo
• Organic energy compound, for short
• Court sport grp
• Sports org. hidden in "great play"
• Court tourney org
• Org. for Nadal or Federer
• Org. for Nadal, Murray and Federer