Wimbledon's massive Monday, featuring all 16 fourth-round matches, is typically the best day in tennis. But this Saturday, about 10 miles to the north in the O2 Arena, could come close.
It's the semifinals of the Barclays ATP World Tour Finals, two delicious matchups -- a late, great treat for tennis fans in this 11th month of the 2015 season.
After Stan Wawrinka's gritty but hardly surprising, 7-6 (4), 6-4 victory over Andy Murray late Friday night in London, the grid is set:
It's No. 1 Novak Djokovic versus No. 5 Rafael Nadal (9 a.m. ET on ESPN3) and No. 3 Roger Federer against No. 4 Wawrinka (3 p.m. ET on ESPN3).
That's a total of 43 Grand Slam titles among the players, compared to a total of two (both Murray's) from the group of four departing players that also included Kei Nishikori, Tomas Berdych and David Ferrer.
Here's how the matches break down:
Djokovic versus Nadal
This one (unless you are a Fed Fanatic) could be seen as essentially the final.
Djokovic -- who has won 24 of his past 25 encounters on tour -- comes in on fire. Nadal, who failed to win a Grand Slam singles title for the first time in 11 years -- has been scuffling. Djokovic has won all three of their meetings this year, and all seven sets as well.
But a curious thing happened this week. Actually, Rafa happened. He has been bouncing around the court in London and has that old, predatory gleam in his eye.
"It's a fact that he's been playing better and he's been raising his level ever since [the] US Open," Djokovic said Thursday in his news conference. "The couple of matches, first couple of matches he played here against Wawrinka and Murray showed that he feels more confident, shows that he's starting to miss less, serve efficiently, use his forehand much better.
"I know that; I've been watching. I know what is expecting me. We played so many times."
Yes, these two have a history.
There was the marvelous 2009 Madrid Masters semifinal, the longest three-set match ever, at 4 hours, 3 minutes, that went to Nadal. The breathless 2012 final at the Australian Open, which Djokovic won 7-5 in the fifth set. The 2013 phenomenal semifinal at Roland Garros that Nadal took 9-7 in the fifth.
Nadal leads the series 23-22, but the question is this: Can Rafa lift his game to those previous, dazzling standards?
Perhaps not. He looked a little sluggish in Friday afternoon's three-set win over Ferrer, which required an invasive 2 hours, 37 minutes. Djokovic had the day off.
"The last two matches haven't been on the level desired," Djokovic said, "but still managed to win two and lose one and I'm in semifinals. With the amount of wins I had this year, with the quality of tennis that I've played, I'm going to approach that match really optimistically as I always do."
Prediction: Djokovic in three.
Federer-Wawrinka
It's a blast from the past, a Switzerland Davis Cup practice from a year ago, when these teammates took home their first title.
Wawrinka advanced to the Barclays semifinals for the third straight year, while Murray is headed to the Davis Cup final against Belgium. After a low-energy opening loss to Nadal in round-robin play, the 30-year-old Wawrinka seems eager to build on the season that produced his second major title, at Roland Garros.
In Paris, Wawrinka defeated Federer in straight sets; Federer won their other two matches this year in straights, at Rome and the US Open, and holds a decisive 17-4 career head-to-head edge.
Last year, looking ahead to the Davis Cup finals, Federer granted Djokovic a walkover in the Barclays final. This year, the 34-year-old has no complaints.
"Honestly," Federer said Thursday, "I feel really good about my body. I've got the perfect schedule. I'm off before the semis, which is huge. Now you're looking at potentially a maximum of two more matches and the season's over then. It's easy for the mind now, in my opinion. There's no best-of-five-set matches to look forward to, so it should be pretty easy.
"It's going to be tough in the sense to win. But for the body, I'm in an ideal situation looking at the semifinal match."
Prediction: Federer in two.
Mad scramble in doubles
No. 1 seeds Bob and Mike Bryan qualified second in the Group Ashe/Smith on Thursday but had to wait until Friday evening to learn who their Saturday opponent was.
In the afternoon session No. 3 seeds Ivan Dodig and Marcelo Melo beat No. 7 Marcin Matkowski and Nenad Zimonjic 3-6, 7-5, 10-6. Later, No. 2 seeds Jean-Julien Rojer and Horia Tecau handled No. 6 Pierre-Hugues Herbert and Nicolas Mahut 6-4, 7-5.
That means it will be the Bryans versus No. 2 Rojer and Tecau in one semifinal. The California twins are 5-0 against this team -- all matches coming in 2014. In the other, it's Rohan Bopanna and Florin Mergea -- who were seeded dead last heading into this event but qualified first in Group Ashe/Smith -- against Dodig and Melo. Bopanna and Mergea are 1-2 head-to-head, having lost both matches in 2015.
Predictions: Bryans and Bopanna-Mergea advance to the Sunday final.