SHEFFIELD, England (AP) — For those who had doubts about Vincenzo Nibali's current form, there is little left to fuel the skepticism.
The former Vuelta and Giro winner, who waited until last month to post his first win of the season at the Italian championships, made the most of his rivals' wait-and-see attitude in Sunday's Stage 2. Nibali claimed a first stage win on the Tour and seized the race leader's yellow jersey.
Here are five things to know about Sunday's and Monday's stages:
SHARK ATTACK: Nibali launched a perfectly-timed attack to win Stage 2 ahead of his main rivals, completing his collection of grand tours' race leader jerseys.
The canny move, ignited after the final climb of a hard day of racing featuring nine short but brutal ascents, paid off as Nibali took charge of the race. Overall, he's two seconds ahead of a group of 20 riders, including defending champion Chris Froome and two-time winner Alberto Contador.
Contador and Froome tested each other in the Cote de Jenkin Road, five kilometers (three miles) from the finish line, before Peter Sagan tried his luck in vain. Nibali, who has been nicknamed "The Shark", then powered away from the group, making the most of his rivals' hesitation.
Following a crash at the Tour of San Luis earlier this season and the birth of his first daughter Emma Vittoria, critics of the classy Italian had questioned his form in the months leading to the Tour.
"It was a fabulous day for me, I led a good move," said Nibali, the 2013 Giro champion. "It was difficult. There was a lot of headwind. I was lucky to attack at the right moment."
Behind, world champion Rui Costa led the chase but it was too little, too late and Nibali had enough time to celebrate as he crossed the line in Sheffield ahead of Greg van Avermaet and Michal Kwiatkowski.
CONTADOR AND FROOME IN THE MIX: Contador and Froome were happy not to take the race lead too early and to leave Nibali's Astana team with the responsibility of controlling the race.
"They were all hesitant because nobody wanted the jersey," said Team Sky boss Dave Brailsford. "Nibali's got it for two seconds and Astana will have to now defend it, which is pretty good for anybody else. Perfect. They've got to work, but the question is whether they'll defend it, we'll wait and see tomorrow, but it's ideal for us."
Contador was content to be in good health after two days of dangerous racing among hundreds of thousands of fans lining narrow and undulating roads.
"Alberto did not want to win this stage nor take the jersey," said Contador's press officer Jacinto Vidarte, adding that the first stages had gone well so far for the rider.
"Alberto is quite satisfied because over the past two years he fell off during the first week of racing," Vidarte said.
ALLERGIC REACTION: On the Tour de France roads, danger also comes from the air.
Italian Alessandro Petacchi, one of the most decorated sprinters in the bunch, was stung by a flying insect during the first stage and developed a severe allergic reaction that could end his Tour prematurely.
After finishing last in the first stage more than 14 minutes behind the winner, Petacchi lost nearly 20 minutes on Sunday.
Petacchi's team doctor said he was treated with antihistamines because anti-doping rules are preventing him from using injections of cortisone.
"We are happy with these rules," Helge Riepenhof said. "Antihistamines work quite well but one negative side effect is that they make you very tired. And Alessandro is definitely someone who will sleep all day if you give him one of these tablets. So we are quite limited with this if we want him to be good on his bike."
At the 2001 Tour, Jonathan Vaughters had to withdraw from the race after being stung in the eye by a wasp during a training ride.
The American was allergic and his eye quickly swelled up, forcing him to receive a prescribed injection of cortisone. Knowing that he would test positive, Vaughters had to pull out of the Tour.
SAGAN GOES GREEN: Peter Sagan's main objective at the Tour is to win the best sprinter's green jersey for a third consecutive time. The colorful Slovakian grabbed it after attacking in the finale, although he had to settle for fourth place following Nibali's attack.
"Every day it's hard to win a stage at the Tour de France, especially now that I'm closely watched out," Sagan said. "Nobody would work with my team. I'm very happy for Vincenzo who is a very good friend since we were teammates before."
ROYAL SPRINT ON THE MALL? When Tour organizers revealed the race course last autumn, it looked like the 155-kilometer (96.3-mile) third stage between Cambridge and London was tailor made for Mark Cavendish. But with the Manxman out of the race, it's now down to strong men like last year's Tour best sprinter Marcel Kittel and Andre Greipel to seize a prestigious win in the British capital before the peloton crosses the Channel.
Kittel relinquished his yellow jersey on Sunday after a miserable day in Yorkshire and will be keen on adding to his tally of five stages.
Once the peloton has passed the Olympic Park, it heads for the city center, with the final kilometers taking riders along St. James' Park and past Buckingham Palace for a spectacular finish.