MELBOURNE, Jan 28 (Reuters) - Novak Djokovic said on ‌Wednesday that the off-season can be a "two-edged sword", with the physical and mental workload players undertake to improve ‌their game sometimes leaving their bodies under strain before the new season even begins.

The 38-year-old marched ‌into the Australian Open semi-finals in search of a record-extending 11th title at Melbourne Park and a standalone 25th Grand Slam crown, but his progress has come amid a streak of unfortunate injuries for his opponents.