French Open: Serena Williams on win over Kiki Bertens

Serena Williams admitted to having "some issues" with an adductor injury after appearing to struggle in her straight-sets French Open semi-final victory against Kiki Bertens.

The reigning champion looked out of sorts on Friday, particularly in the first set of her 7-6 (9-7) 6-4 triumph on Court Philippe Chatrier.

She now faces Garbine Muguruza in Saturday's final, having beaten the Spaniard in the 2015 Wimbledon showdown.

Asked about her possible fitness issues, Williams – whose last-four opponent was carrying a calf problem – said: "Yes, I have had some issues, but it is what it is. I think it's survival of who can do the best.

"I think the first set was obviously really crucial.

"She's had a couple of big wins in this tournament. Being in the semi-finals of a grand slam and having nothing to lose just really makes a big difference."

Bertens, who beat four seeds in a promising tournament for the 24-year-old, conceded her injury was capitalised upon by the world number one.

"I think it was really smart from Serena to hit the drop-shots," she said. "I had some problems with it.

"It was pretty tough. We were warming up this morning and we were discussing, 'Okay, are we going to play or are we not going to play?' I was like, 'Okay, I want to go on court. I don't want to regret it afterwards that I didn't do it'.

"So I'm really happy that I went on court. I think I played a really good match, played really aggressive tennis, so I think I can be proud of myself."