Novak Djokovic's bid to claim a landmark 100th ATP title remained on track as he overcame talented teenager Jakub Mensik in the quarter-finals of the Shanghai Masters.
The Serbian fourth seed lost the first set on a tie-break to the Czech 19-year-old but battled back for a 6-7 (4-7) 6-1 6-4 victory.
Djokovic, 37, will face American world number seven Taylor Fritz in Saturday's second semi-final.
Fritz, 26, comfortably beat Belgium's David Goffin 6-3 6-4 on Friday to book his place in the last four. It extended a run that has seen Fritz progress past the third round for the first time in Shanghai.