What To Watch For On Day 12

© 2017 Michael Cummo/BNP Paribas Open

After Nick Kyrgios' withdrawal from his quarterfinal against Roger Federer due to illness, a busy Friday continues at the BNP Paribas Open with Jack Sock and Kei Nishikori's match at 2pm, which will determine who will face Federer in the semifinals. Plus men's doubles semifinals, as well as women's singles for the night session. Here's a list of what to watch on Day 12.

ELENA'S EVOLUTION
She stood atop the doubles podium at the Rio Games in 2016, Elena Vesnina having captured the gold medal with countrywoman Ekaterina Makarova. But the 15th-ranked Russian is hardly a doubles specialist. She cracked the Top 20 in singles last year -- reaching the Wimbledon semis -- and on Thursday in Stadium 1 ousted resurgent American Venus Williams 6-2, 4-6, 6-3, her fourth win over the elder Williams sister in six tries. Next up for the 30 year old is surprise semifinalist Kristina Mladenovic. "She's on fire. So am I," said Vesnina, who won her two previous encounters with the Frenchwoman. "It isn't going to be an easy match, but I'm really excited to be in the semifinals."

“Vesnina”
READ: FIVE QUESTIONS WITH VESNINA

KEI TO SUCCESS?
Expect some ballistic baseline exchanges when No. 4 seed Kei Nishikori faces No. 17 Jack Sock in the BNP Paribas Open quarterfinals. These are two of the ATP Tour's biggest hitters off the baseline. "I don't know anybody that I could say is quicker than him as far as his movement, and I do think he has the best weapon in that forehand," said ESPN's Chris Evert of Sock. The American claimed his most recent encounter with Japan's top player -- the 2014 US Open runner-up -- at the Shanghai Masters in 2014, and is rolling here in the desert. "Very, very solid player, very consistent player," Sock said of his opponent. "He's Top 5 for a reason. When we played in Shanghai and I was able to win, I was playing aggressive, big forehands, coming forward when I could, just trying to keep him back behind the baseline and kind of try and move him side to side. If he's moving in, stepping into balls, forehands or backhands, dictating points, then it's going to be trouble for me."

Nishikori

SERVING NOTICE
Since her run to the 2016 US Open final, where she pushed world No. 1 Angelique Kerber to three sets, Karolina Pliskova has established herself as one of the most dangerous draws in the game and the WTA Tour's most dominant server. On paper, the ace queen comes into to this semifinal clash as the favorite, but the 6-foot-1 Czech won't overlook her opponent -- two-time Grand Slam champ Svetlana Kuznetsova, who after more than a decade-and-a-half on the circuit is loving her time on court more than ever. With a title at the Indian Wells Tennis Garden, the Russian veteran -- a runner-up here in 2007-08 -- would rise to No. 6 in the rankings. "I can see she's really enjoying the tennis, even if she's not always playing well. She's really tough now for every girl to beat," said Pliskova of her opponent. "Right now, she looks really happy. You can even see it with the results. So she improved the last year-and-a-half so much."

NOT MEANT TO BE
Fans were looking forward to the battle between Roger Federer and Nick Kyrgios, but the Australian withdrew from the tournament Friday morning when he announced that he was suffering from an illness and not fit to play. Federer gets a walkover to face either Nishikori or Sock in the semifinals. Kyrgios expressed his disappointment in a message posted on Twitter, with Federer responding to the post, wishing him well.

GETTING SCHOOLED
The BNP Paribas Open Collegiate Tennis Challenge presented by Oracle gets underway on Friday and runs through Sunday. The collegiate showcase will feature the top men's and women's players from Baylor, USC, Cal, Oklahoma, University of South Florida, Tulsa, SMU and Purdue. Play begins at 8:30 a.m., and admission is free with BNP Paribas Open tickets. Grounds passes can be purchased for $20 per day.