US Open 2017: Roger Federer's first-round five-set battle brings his fitness under the spotlight

Roger Federer had a strange start to the 2017 US Open — in his opening game against 19-year-old American Frances Tiafoe, he committed four unforced errors to get broken.

What followed was an even stranger match as the 19-time Grand Slam champion was stretched to five sets in the opening round at Flushing Meadows for the first time since his debut against Peter Wessels in 2000. Read more.