The thick fog that engulfed London on Sunday found its way to Jo-Wilfried Tsonga at the start of the World Tour Finals. In the ebullient Frenchman's words, he "didn't put one ball in the court" against Roger Federer in a first set that lasted slightly longer than the warm-up.
Tsonga continues to spot Federer opening sets, and three straight times now he hasn't been able to fully recover. Federer, who blew a two-set advantage to Tsonga at Wimbledon, marked his 10th straight appearance at the year-end championships with a 6-2, 2-6, 6-4 win.
Federer's rival, Rafael Nadal, had a similarly topsy-turvy time against Mardy Fish in the nightcap. Playing for the first time in more than five weeks, Nadal and his ailing tummy triumphed 6-2, 3-6, 7-6 (3) in nearly three hours.
Here are five thoughts from an exciting opening day, when all four matches -- singles and doubles -- went to three sets.
More drama for Nadal in London
Drama and Nadal in London go hand in hand.
Or should that be controversy?
Last year at Wimbledon, remember the medical timeout he took against Philipp Petzschner -- before the German was due to serve -- in the fourth set? Petzschner, leading two sets to one, was immediately broken, and Nadal cruised in the fourth and fifth sets.
This summer at the All England Club, Juan Martin del Potro, a probable opponent of Nadal's in the upcoming Davis Cup final, was visibly ticked when the Spaniard called for the trainer prior to a first-set tiebreaker, which Nadal ultimately won.
On Sunday, Nadal hurried off court for a bathroom break leading 2-0 in the third set, making Fish wait. And although Fish broke back for 2-1, Nadal's critics are sure to note his latest breach of tennis etiquette.
Nadal apologized in an on-court interview after the match and said he "felt terrible from the stomach."
Fish didn't make anything of it.
"I didn't think he was trying to ice me," Fish said.
Given his physical state -- and there's nothing to suggest Nadal was faking it -- it's hard to evaluate his performance. But whether it was his ill health or recent inactivity, or a combination, for most of the affair he lacked depth on his groundstrokes. He also, strangely, stuck with his favored crosscourt forehand, which went straight into Fish's strength on the baseline, his backhand.
Toward the end of the third set, Nadal clearly made an effort to pick on the Fish forehand, and it paid dividends. Nadal was passive, too, playing a lot of defense, and stayed away from the net, even when Fish was in trouble on the baseline.
Sheer will and experience got him through.
"I feel not very well, no?" said Nadal, who faces Federer on Tuesday evening. "I really need to come back to the hotel and rest a little bit because I played for one hour suffering a lot."
As for Fish, his hamstring held up fine. He'll be lamenting not capitalizing on a break advantage midway in the third set.
Fed does enough
It wasn't a bad performance by Federer, who had soccer superstar and former Gillette confrere Thierry Henry in his box. (Boris Becker, an analyst for Sky, mentioned in a particularly amusing moment that Henry played for the New York "Cosmos" instead of the Red Bulls.)
For the most part, Federer served well, winning almost 80 percent of points behind the first delivery. And serving well is pivotal indoors.
His strategy on serve was simple: Go to the Tsonga backhand. In fact, it looked like Rafa facing Fed. Such was Federer's intent to keep going to the backhand on serve that he missed wildly on the ad side on several occasions. Federer's kick serve to the Tsonga backhand earned him a flurry of easy points.
There was, though, a worrying dip, and you can blame it on the forehand. Cruising at 6-2, 1-1 and serving at 30-0, Federer was later broken. Twice in succession he erred on forehands down the line.
In the final game of the encounter, Federer simply got lucky on the Tsonga serve.
Tsonga's risk and reward
That Tsonga can't play a smooth, steady match against the elite isn't all that surprising. He's such a high-risk player.
But just just as in the final of the Paris Masters this past week, his first set was a real stinker, even taking into account Tsonga's intermittent troughs. Through five games, his first serve percentage stood at 13.
Would it surprise you to learn he was 4-1 down?
Don't blame nerves. Tsonga, in his second year-end tournament, was all smiles as he walked on court and appeared relaxed in his prematch TV interview. He had a much better warm-up than in Bercy, when he shanked balls left and right. His expression as he left the court in defeat suggested he knew he missed a chance.
Tsonga did, though, hit the shot of the match, punishing a crosscourt backhand in the second set, only to -- on the ensuing point -- bury a second-serve backhand return into the bottom of the net.
"It's not always in your control when you play Jo," Federer said. "That's the beauty of it. I kind of enjoy that to some degree."
He enjoyed it much more Sunday than in June.
Bring on the doubles
The doubles players in attendance must be in heaven. They get to compete in front of packed houses at the O2 Arena, a change from the empty stands during the regular season.
Nestor and Mirnyi prevailed, reversing a 6-3 deficit (two mini-breaks) in the match tiebreaker.
But Bopanna and Qureshi won the point of the encounter, and what will probably go down as the point of the tournament.
Qureshi, chasing an angled Nestor backhand volley in the match tiebreaker, jumped over a side railing after throwing up a defensive lob on the full stretch. He quickly jumped back over the railing and into the court in time to see his partner loop a crosscourt backhand past a stretched Nestor at the net.
Mohamed "Hollywood" Lahyani, the chair ump you either love or loathe, offered up the quote of the day during the coin toss between Nadal and Fish.
Sporting a microphone so the crowd could hear, Lahyani said to the players, "If you have any questions, you know where to find me."
The arena broke into laughter, and Nadal smiled -- for one of the few times of the evening.
London-based Ravi Ubha covers soccer and tennis for ESPN.com. You can follow him on Twitter.