INDIAN WELLS, CA, USA -- Former World No.1 Venus Williams of the United States will get to continue her quest for a first-ever BNP Paribas Open title after a 6-4, 6-4 win over Germany’s Mona Barthel in the fourth round at Indian Wells on Tuesday.

In her press conference, Williams answered in the affirmative when asked if she felt she played well, but added that Barthel "was playing very well too, actually. She forced the issue on every point, didn't make a lot of errors, played defensively when she had to, played offensively. I was really impressed with her game. I was happy to come through. It wasn't easy."

Williams, who has reached the semifinals three times at Indian Wells, including last year, extended her undefeated record against Barthel to 4-0 after her one-hour-and-44-minute victory. The seven-time Grand Slam champion has now won four consecutive matches for the first time since her semifinal run at the BNP Paribas Open last year.

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Williams and Barthel had a matching 26 winners apiece in the bruising groundstroke battle. But it was the American who gained more opportunities on return throughout, converting four of 10 break points, doubling Barthel, who connected on two out of five.

"I was pretty determined this year," Williams added. "I haven't played that much, so I wanted to make it count. It's not going to get any easier from here, so I just have to continue to raise my game."

In the quarterfinals, 38-year-old Williams, currently ranked World No.36, will face the winner of the night match between two Top 10 players: No.8 seed Angelique Kerber of Germany and No.9 seed Aryna Sabalenka of Belarus.

After an early exchange of breaks leading to 2-2, Williams jumped out to a commanding 5-2, double-break lead thanks to some fiery forehands. With Williams serving for the set, though, it was Barthel who used her own powerful forehand to claw one of those breaks back and extend the set.

After a hold by Barthel, Williams stepped to the line for a second chance to serve out the set. On this occasion, the American legend would not falter, reaching double set point with a backhand winner, and converting her first opportunity with another winner from that wing down the line.

World No.97 Barthel continued to hang with Williams in the second set, showing off her hard-hitting game that once had her ranked in the Top 25. But Williams started to find exceptional range on her forehand, queuing up break points at 3-3. On her second chance, a crosscourt backhand set up a forehand winner for the American to break for 4-3.

Serving to stay in the match at 5-3, Barthel sent a forehand long to give Williams a match point. But the German stayed aggressive and reeled off three straight points to extricate her from that troubling situation and hold for 5-4, prolonging the clash.

However, Williams did not blink, and quickly grasped two more match points in her next service game. Barthel misplayed a return into the net on Williams’s second match point of the encounter, sending the former top-ranked player in the world into the Indian Wells quarterfinals for the fifth time in her storied career.