MELBOURNE—British teenage tennis star Emma Raducanu was unable to find the solution to her latest Grand Slam puzzle on Thursday, as a combination of a blistered racket hand and an inspired Danka Kovinic derailed her Australian Open plans in the second round. The 17th seed, who rocketed to fame by winning last year’s U.S. Open as a qualifier without losing a set, gritted her teeth through the discomfort to stay in contention in a tense clash but fell to a 6–4 4–6 6–3 defeat. Nineteen-year-old Raducanu, who beat former U.S. Open champion Sloane Stephens in the first round to take her Grand Slam main draw record to an incredible 11–1 from three events, needed treatment after the fifth game of the first set. With her hand taped she was unable to deliver her usual baseline power and resorted to slicing virtually every forehand. Incredibly she turned the shot of choice …