HIROSHIMA, Japan – No.1 seed Zhang Shuai overcame defending champion and No.6 seed Zarina Diyas to secure a place in the semifinals of the Hana-cupid Japan Women's Open, but revealed she had to go through the pain barrier to do so.

It was a match punctuated by frustrating rain delays, though Zhang kept her nerve better through these complicated early stages to claim the opening set. And the 29-year-old again showed her mental toughness in a tighter second set to complete her first victory over the Kazak player in three attempts.

Indeed, even getting out on court was something of a minor victory for Zhang as she revealed she was undecided whether she would play mere hours before the match.

"Yesterday my leg was really painful in the doubles match, so this morning I was still deciding whether to play or not," she confessed. 

Playing, though, proved worthwhile.

"It was a nice game for me today. I played really well. I lost to her here last year, so I had nothing to lose," she said.

Earlier rain saw the match moved onto Court 3 and the first of a handful of stoppages arrived after barely five minutes of play. The staccato rhythm that the showers brought seemed to suit the Chinese player better, with a combination of her power and a high unforced-error count from Diyas allowing her to piece together a five-game run that saw her take command of the set.

It was not all straightforward, but when forced to turn the level of her game up, such as when she faced break points, Zhang seemed capable of doing so.

Her momentum was arrested, however, by a half-hour break that saw the players finally leave the court. Her serve was broken on return, and though she held out to claim the opener, there had undoubtedly been a shift in the balance of the match. 

The second was altogether more competitive, with Diyas content to use looping shots to contain the power of her opponent. Although she fell a break down, she got it back rapidly and for a period seemed to take command, winning a break point in the sixth game that was lost only when she narrowly missed. 

But as the set wore on, Zhang began to deal increasingly well with the new challenge presented to her and muscled her way to 5-5.

Another brief rain stoppage played into the top seed’s hands, with a fortunate net cord and a double fault setting up a break point opportunity that was saved by a Diyas winner. Given a second chance, though, Zhang took it.

With the quality of tennis apparently ever on the rise, she saved a break point en route to securing the match.

She attributed her adaptability, which was arguably decisive in the second set and the match, to playing doubles at the US Open, which aided her net play. 

"Playing doubles in New York last week really helped me improve," she said. "It helped me improve the volley smash. When I came to the net I started to win a lot of points, so that made a big difference."

Next up for her is Amanda Anisimova, who had beaten Anna Karolina Schmiedlova, 6-3-, 6-1 earlier on Friday.