Complex sentence: At a set and a break down, Nadal sustained a back injury that saw him swiftly lose the second set, but he recovered to win the third and fought hard before Wawrinka prevailed in four sets.
Split into simpler sentences: At a set and a break down, Nadal sustained a back injury that saw him swiftly lose the second set. He recovered enough to win the third and fought hard before Wawrinka prevailed in four sets.