"I just don’t understand." Serena Williams speaks for the first time about US Open drama.

Serena Williams has spoken out for the first time since her US Open on-court drama, once again calling for men and women to be treated equally in tennis.

The headlines following this year’s US Open women’s singles final were dominated by an argument Williams had with umpire Carlos Ramos, eclipsing the first grand slam win of Japan’s Naomi Osaka.

Williams was furious when she was given a coaching violation early in the second set after a hand gesture from her coach Patrick Mouratoglou.

She was docked a point for a second violation when she smashed her racket after dropping serve at 3-3.

She then received a game penalty for her outburst in which she called Ramos a “thief”, putting Osaka within one game of winning.

Williams used her post-match press conference to suggest men avoid punishment for similar on-court behaviour.

Following the game, Mouratoglou told ESPN he had been giving Williams instructions but believed she had not heard them.

In an interview with The Project, which will air in full on Sunday, Williams remained defiant.

Back from US & I can finally reveal I was there to interview Serena Williams, her first since US Open. More tonight on Sunday @theprojecttv

— Lisa Wilkinson (@Lisa_Wilkinson) September 16, 2018

She defended her initial claim that Mouratoglou was not coaching her during the match.

“He said he made a motion,” she said. “I don’t understand what he was talking about. We’ve never had signals.”

She also reiterated her belief that female players are not treated equally to men.

“I just don’t understand… If you’re a female you should be able to do even half of what a guy can do,” she said.

“I can’t sit here and say I wouldn’t say he’s a thief because I thought he took a game from me.

“But I’ve seen other men call other umpires several things.”

Williams also spoke at the National Retail Federation Show in Las Vegas on Friday.

“I feel it’s really important to stand up for what you believe in and especially if you believe in something that can affect the future and affect a lot of people in the future,” she said at the event. “For me that’s what it’s all about, that’s kind of what my career has always been about.”

Last week Ramos, the umpire at the centre of the controversy, spoke about the issue to Portuguese paper Tribuna Expresso.

Ramos said he stood by his decisions and believed he treated all players equally.

“I’m fine, given the circumstances,” he said. “It’s a delicate situation, but a la carte arbitration does not exist. Do not worry about me!”