In their first match since the 2016 BNP Paribas Open final, No.10 seed Serena Williams of the United States picked up another win over long-time rival Victoria Azarenka of Belarus, winning 7-5, 6-3, in the second round of the 2019 edition at Indian Wells on Friday.

In the 22nd meeting between the two former World No.1’s, each a two-time champion at this event, it was Williams who extended her head-to-head lead to 18-4 over World No.48 Azarenka after two hours and six minutes of an intense and bruising baseline battle.

"You can't really enjoy it, because then you'll lose focus," Williams told the press, when asked about the classic clash. "You've got to kind of stay in the moment, you know. And it's important to -- like, sometimes you realize, 'Oh, my God, this is going to be a classic.' But you can't let your mind go there, because you wouldn't want to watch it in the future," she said with a smile.

Williams chalked the win up to "just being professional more than anything, and just wanting to be out there and continuing to be out there. I think really, literally, that's what it boiled down to today."

23-time Grand Slam champion Williams had 39 winners to Azarenka's 25, but Azarenka had just 24 unforced errors to Williams' 45. Williams, however, was clutch on her biggest opportunities, converting half of her 12 break points, while Azarenka was just 4-of-15 on her own break chances.

"Serena pushes me to play my best tennis," Azarenka said during her post-match press conference. "You know, she really won. She deserved to win. She played better on those important moments. I felt that every game was ad, deuce, ad, deuce. It was all about who was going to take that chance, and she took them a little better today."

The difficult draw for Williams will continue in the third round, as she will have to face another former World No.1: No.20 seed Garbiñe Muguruza of Spain. Two-time Grand Slam champion Muguruza dispatched American wild card Lauren Davis in straight sets earlier on Friday.

"It means I have just been on tour a long time to play a lot of former No. 1's," Williams noted.

The first set was chock full of blistering rallies, as both women put the pedal to the metal on their returns and groundstrokes throughout. After holds for 1-1, there were four straight service breaks as the ball was being maneuvered around the court brilliantly by the combatants.

Williams needed to fend off two break points at 3-3, both with backhand crosscourt winners, to stop the streak of service breaks and hold for 4-3. That seemingly paid dividends after another backhand crosscourt winner on break point in the next game put the American up 5-3 and gave her a chance to serve out the set.

But incredible defense and groundstroke depth by Azarenka in the next game allowed her to come out on top in some outrageous rallies, and the Belarusian clawed back on serve. Azarenka followed up with a love hold for 5-5 and the set was once again dead even.

Another grueling Williams service game followed, and the American came up with outstanding forehands and serves to stave off four break points and hold for 6-5. At this juncture, Williams took advantage of her lead, blasting back-to-back return winners from 30-30 to break Azarenka for a fourth time and earn a hard-fought one-set lead after 72 impressive minutes.

Azarenka started the second set off with a break, determined to continue the top-notch play which nevertheless caused her to fall a bit short in the first set. But Williams was on a mission, breaking right back for 1-1 after a powerful backhand return winner.

The players held serve with relative ease until 4-3, where Williams garnered chances to take a crucial lead. There, one break point went begging with a netted return, but the American earned another shot after a huge crosscourt return, and took the game after Azarenka fired a backhand mistake into the net.

Serving for the match at 5-3, Williams let two match points fall by the wayside, the second one with a double fault, and Azarenka clutched two break points to get back on serve. But after Williams saved the second break point with an ace, her vaunted delivery came back with a vengeance, and she used two incredible serves to finish out the closely-contested match.