Kei Nishikori was given a fright by lucky loser Donald Young in the Japan Open first round on Monday, before coming back from a set down to advance.
The home favourite has triumphed twice previously at this ATP 500 event - in 2012 and 2014 - but he was looking at an early exit before recovering to prevail 4-6 6-2 6-2.
American Young was only playing after Nicolas Almagro pulled out through illness, but he appeared keen to make the most of his second chance as a break in game 10 handed him the first set.
That was as good as it got for the world number 81, however, as Nishikori raced into a 5-1 lead in the second, eventually levelling the match by converting his fourth set point.
Five successive games from 2-1 down in the decider sealed Nishikori's passage, and he will now face Joao Sousa, who also came from a set down to win - 4-6 6-3 6-3 against Martin Klizan.
The other two matches on Monday saw Fernando Verdasco oust Go Soeda 6-7 (2-7) 6-3 6-3, while Marin Cilic saw off Benoit Paire 6-0 4-6 6-3.