Facing the most, experienced woman in the Wimbledon field - 40-year-old Kimiko Date-Krumm of Japan - Williams was mired in a three-set struggle that lasted nearly three hours Wednesday, a tight, high-quality contest brimming with the sort of at-the-net, classic grass-court play seen so rarely nowadays.
Wimbledon has come to expect fighting instincts and effortless power from Serena Williams but the raw tears she shed after beating Aravane Rezai on Tuesday betrayed just how much torment she has suffered since holding the trophy aloft last year.
The John Isner against Nicolas Mahut rematch inevitably failed to live up to last year's historic clash when American Isner needed only just over two hours to book his place in the Wimbledon second round on Tuesday.
Rafa Nadal made a dazzling start to his Wimbledon title defence with an easy win over American Michael Russell on Monday before home favourite Andy Murray produced some indoor fireworks to join the Spaniard in the second round.
Li Na will have wiped off her deep purple nail polish by the time she opens her Wimbledon campaign but the weight of expectation on her shoulders after becoming the first Asian player to win a grand slam title will not be so easy to remove.