Serena Williams and Roger Federer on Centre Court.
Venus Williams and Novak Djokovic on No. 1 Court.
There's plenty to watch on Day 5 at Wimbledon, partly because rain has affected the schedule and organizers are still trying to play catch-up.
The Williams sisters, who have won a combined 11 titles at the All England Club, should get to watch each other play Friday. Venus, seeded No. 8, is up first on Court No. 1 against 29th-seeded Daria Kasatkina of Russia in the third round. The top-seeded Serena is second on Centre Court against another American, Christina McHale, in the second round.
Venus is a five-time champion at the All England Club, but last went as far as the quarterfinals in 2010. Her career has been slowed in recent years by Sjogren's syndrome, a condition that can cause joint pain and saps energy.
On Friday, she'll be back on one of the bigger courts after spending Thursday winning on Court 18, one of the smaller stadiums that is still considered to be a show court.
"I'm not so much into disrespect. I'm willing to play anywhere, any time," said Venus, who was asked about the lack of top men's matches on the outside courts.
"It's not the ideal schedule for the women. We'd like to see equal amount of matches. We don't want more, just the same amount, that's all."
Little sister Serena, a six-time Wimbledon champion and the defending champion, will be second in the main stadium. Although Serena is the title favorite, she has lost in the Australian Open and French Open finals this year and last won a major title — her 21st — at Wimbledon last year.
Here are some other matches to look for on Friday:
ROGER AND NOVAK: Federer and Djokovic, who have won a combined 10 titles at Wimbledon, will each follow a Williams sister on court.
Federer, who lost to Djokovic in the past two Wimbledon finals, will face Daniel Evans of Britain on Centre Court. Djokovic will take on 28th-seeded Sam Querrey of the United States on Court No. 1.
Both Federer and Djokovic are chasing history, as usual. Federer is looking for a record eighth Wimbledon title, while Djokovic is on course for a calendar-year Grand Slam — a feat that has not been done since Rod Laver in 1969.
ANOTHER WIMBLEDON CHAMPION: There will be another former Wimbledon champion on court Friday when 10th-seeded Petra Kvitova takes on Ekaterina Makarova on No. 2 Court in the second round.
Kvitova, who is from the Czech Republic, won the title at the All England Club in 2011 and '14. Last year, however, she lost in the fourth round — her worst result at Wimbledon since back-to-back first-round exits in 2008-09.
DEL POTRO VS. WAWRINKA: The opening match on Centre Court will be between a pair of players who have combined to win the other three major titles, but never Wimbledon.
Stan Wawrinka, a former Australian Open and French Open champion from Switzerland, will take on 2009 U.S. Open champion Juan Martin del Potro of Argentina in the second round.
Del Potro has won three of his five matches against Wawrinka, but the fourth-seeded Swiss won their only matchup on grass at Wimbledon in 2008.