Suh Hyo-won, Jang Woo-jin provide first-session ITTF Finals surprises in the round of 16.
Ishikawa only managed to win the second game, as Suh comfortably clinched an 11-8, 3-11, 11-9, 11-5, 11-5 victory.
"I faced her quite recently at the Women’s World Cup and studied the match to prepare for this. I was quite confident going into this," Suh told the ITTF after the match.
In the men's draw, world number 18 Jang staged a comeback from 3-1 down to beat tournament fourth seed Harimoto Tomokazu in a match that went the full seven games.
The fifth game was a big turning point for Jang, who was on the verge of elimination.
He pushed Harimoto hard, eventually hanging on to take the game 12-10.
That seemed to break his opponent, as Jang eased to comfortable margins in the sixth and seventh games, winning 6-11, 2-11, 11-7, 7-11, 12-10, 11-2, 11-5.
"In the fifth game, 3-1 down 10-8 to him, I thought I would lose the match so I just gave it a go and got some lucky points," Jang admitted.
"I think he got nervous and after the fifth game I had less pressure."
In other results from the first morning session:
(Top photo credit: ITTF)