It was really tough to push myself into it, says Karolina Pliskova. Photo: Andy Wong/AP

SINGAPORE – Karolina Pliskova raced through her opening two White Group ties to secure a WTA Finals semi-finals berth with a match to spare, but the Czech admitted she found it tough to find the motivation for Thursday’s last round-robin encounter that ended in defeat.

After looking imperious as she dismantled Venus Williams and Garbine Muguruza, both by 6-2 6-2 margins, earlier this week, the third seed appeared flat-footed and lethargic as she succumbed to a meek 6-3 6-1 loss to Latvia’s Jelena Ostapenko.

“It was tough. Not only in the second set... I think even in the first,” the 25-year-old told reporters.

“I started pretty well today and had a few break points, so that game was a little bit key to... I don’t want to say first set, but I felt like if I would have made it, the match would be different.

“It was really tough to push myself into it and to play the best tennis if you know you’re qualified. I’ve never been in this situation, so I felt weird today.”

The big-serving Czech needs to wait until Friday to discover who she will face in the semi-finals a day later, but Pliskova was already looking forward to the familiarity of a straight knockout match after her struggles against Ostapenko.

“Finally I think it will feel like normal tournament, and I’m just happy this day is going to be over soon. Tomorrow, I feel like I should practice a little bit more, because I had three quite easy and not long matches,” she added.

“Hopefully, I’ll be ready... I’m sure I’ll feel much better and play much better. Still, I was not even 50 percent today.

“So I talked to my team, but we just want to forget about this match and move on, because I have more important one coming up.”