Hamilton is attempting to win his fourth straight grand prix, and he's right on track to accomplish that feat based on Friday's two practice sessions at Barcelona's Circuit de Catalunya. The Brit topped the time charts in P1 with a lap in 1 minute, 27.891 seconds and had the quickest lap again in P2, doing it in 1:25.524.
"It's been a great day today, and I'm happy to be back in the car after what feels like quite a long break," Hamilton said. "I can feel the positive step forward that we've made with the car, so a big thank you to everyone back at our factories for all of their hard work since China.
"Our two practice sessions today went very smoothly. In fact, I've not had such a good Friday for a very long time. Barcelona is a difficult circuit in terms of the tires, so our running was all about trying to see how long the tires would last. We we were able to make some positive changes with that during P2 this afternoon."
Hamilton has yet win a race at this 2.892-mile, 16-turn circuit. He finished second here in 2007, his rookie season, and in 2011.
Rosberg, the current leader in the championship standings, had the fifth quickest lap in P1 and then placed second on the charts in P2.
"It looks like we are very quick again; however, I personally didn't feel very comfortable in the car today, especially as I had limited running in P1," Rosberg said. "We still have a lot of work to do, and I will be working closely with my engineers to find my perfect setup for the weekend."
One year ago, Rosberg won the pole position for the Spanish GP. Rosberg ran in front for the first 12 laps before Spaniard Fernando Alonso from Ferrari delighted his home crowd by taking the lead. Alonso took command from there, as he crossed the finish line 9.3 seconds ahead of his closest competitor, Kimi Raikkonen from Lotus. Raikkonen is now with Ferrari. Rosberg ended up finishing sixth.
Hamilton enters Sunday's 66-lap Spanish GP just four points behind Rosberg.
Alonso is third in the standings, a distant 38 points behind. He finished third in the April 20 Chinese GP, giving Ferrari its first podium of the season. Alonso was fourth in both practice sessions for the Spanish GP.
"There wasn't much grip on track today, and in general, we struggled a bit more, which was down to a series of factors, including the track being less rubbered-in than usual," Alonso said. "On top of that, we have less aerodynamic downforce than in the past, and in my opinion, the tire choice here is too conservative for this track. Now we face a lot of work to try and optimize the balance of the car and get the most out of it, even if the circumstances are not that favorable to us."
Alonso leads all active drivers with seven podium appearances in the Spanish GP. His first victory here came in 2006 when he drove for Renault.
The start of this weekend for four-time defending F1 world champion Sebastian Vettel was not a good one, as the Red Bull driver made only four laps during P1 due to an electrical problem. The issue continued throughout the day, forcing Vettel to sit out P2.
"We had a simple failure in one of the looms this morning, which caused a short and meant the car stopped," Vettel said. "We had to change the chassis loom, which is a big job, so I wasn't able to go out this afternoon. It's a small failure but a big consequence. There was nothing new on that part of the car. It was something new that happened in that area."
Vettel's teammate, Daniel Ricciardo, was third quickest in both sessions.
Series: Formula One. Date: Sunday, May 11. Race: Spanish Grand Prix. Site: Circuit de Catalunya. Track: 2.892-mile (4.655-kilometer), 16-turn road course. Start Time: 8 a.m. ET. Laps: 66. Miles: 190.825 (307.104 km). 2013 Winner: Fernando Alonso. Television: NBC Sports Network.