Justine Henin would like to see Serena Williams receiving more of a challenge from other players on the WTA Tour, saying the women's game now lacks a consistent group of top players driving each other to play better.

The former No. 1, who at 33 is younger than Williams, praised Williams for staying at the top for so long. "It's something you have to respect. I know that it takes to wake up and still want to do the hard work," Henin told press in Toronto, where she was inducted into the Rogers Cup Hall of Fame.

"I am a little surprised that she still wants to be here, that's for sure," the Belgian said. "She still has the fire. But I am more so surprised we don't have girls—a new generation—that really say, ‘OK, the old ones (are gone). We take (your) place. I think for the game it will be very important that we need two, three, four players behind her that really try to push her much more."

But she does not see many candidates. "There are many girls that can play good tennis, but it's not consistent enough," said Henin. "And I think they don't believe enough."

"She's right," said Simona Halep, who admired Henin growing up. "Because we see Serena is winning everything and we are thinking that we cannot beat her."

Henin named Victoria Azarenka as the player most likely to push Williams, and also likes Halep's game. "Probably Azarenka could do that, and she's the player I see in the best position to do that," Henin said. "Halep is probably the girl that I appreciate the most to watch, because she tries to do different things. She reminds [me of] the way I was playing a little bit, even if there are different things."

The seven-time Grand Slam champion recalled rivalries from when she was on tour, regularly playing finals against players like Williams, Amelie Mauresmo and Kim Clijsters.

"When I was playing, I had the feeling that you were in [the Round of] 16 and really everyone could win the tournament," she said. "It was a great generation. I think Venus and Serena pushed a lot of players to raise their level. They put the game at another level and it was fantastic to be a part of it because we had to push ourselves all the time to get better. And there was Kim [Clijsters], there was a time of [Lindsay] Davenport, [Jennifer] Capriati. There was [Martina] Hingis. There was the Williams sisters, all the Russian girls coming on the tour. There was Mauresmo, [Maria] Sharapova. That was a fantastic time."

And Williams has kept improving, suggested Henin, saying "Maybe she's still even better today than she was a few years ago. It's amazing."

Williams, who is 40-1 for the season, is playing in the semifinals of Toronto against Belinda Bencic.

