Sloane Stephens referred to Serena Williams as a "colleague" and said she has had to block "a lot" of her fans on Twitter after the two had a falling out following the 2013 Aussie Open. The two former US Fed Cup teammates Stephens and Williams both won their matches Sunday to set up a fourth round clash, with the winner advancing to the quarter-finals of the WTA and ATP Tour Indian Wells tournament. Stephens said they are no longer as chummy as they used to be but they have managed to maintain a working relationship. "She`s a competitor; she`s the number one player in the world. She`s what do you call it? ... when you work with someone? A colleague. She`s a colleague." Top seed Williams, who is making her first appearance in Indian Wells in 14 years, needed just 53 minutes to crush world No. 32 Zarina Diyas 6-2, 6-0 and Stephens outlasted former two-time Grand Slam winner Svetlana Kuznetsova 7-6 (7/4), 1-6, 6-4. All three career meetings between the two happened in 2013, including Stephens 3-6, 7-5, 6-4 upset in the quarter-finals of the Australian Open. Stephens ended a 20-match Williams` winning streak with that victory and the two haven`t been buddy-buddy since then. They met later that year at the US Open, where Williams got her revenge, winning 6-4, 6-1. "So much has happened since then. I remember playing well there (Aussie Open), but I think I played better when I played her at the US Open the same year," Stephens said Sunday. "So, I don`t know. I obviously didn`t win, but I thought I played a little more solid in that match." Stephens also praised Williams on Sunday and said it "was an honor" to face the top ranked player in the world in such a prestigious event. She said she is also looking forward to the challenge because she plays some of her best tennis against Williams. "I felt like every match I played against her I have played well," Stephens said. "I mean, it`s always an honor to play No. 1 player in the world. Back in May 2013, Stephens was quoted in a US magazine as saying that after the Australian Open upset, Williams blocked her from social media. "She`s not said one word to me, not spoken to me, not said hi, not looked my way, not been in the same room with me since I played her in Australia," Stephens said.Stephens said Sunday that she now gets a rough ride from Williams` Twitter fans. "Oh, they hate me," Stephens said. "They are the first people to get blocked on my Twitter. I am the queen of blocking. "Okay? You say one bad thing, block. "There is no room for negativity. I understand that they are die hard fans and I appreciate that. I`m sure she does, too. But some of the comments and some of the things are you know so unnecessary. "It comes to the point where you`re on Twitter saying mean things about someone else ... I`m just like I don`t understand it. But die hard fans are die hard fans. "If I was a nobody, I wouldn`t attack a celebrity." AFP