Red Bull look set to continue their dominance in the second half of the Formula One season after Sebastian Vettel headed teammate Mark Webber in Friday’s second practice session for the United States Grand Prix in Austin. Red Bull have already wrapped up the constructors’ championship, while, on the back of an incredible seven-straight victories, a fourth straight drivers’ title already belongs to Vettel.

The real battle now in the remaining two races of the season will be for which team can take second in the constructors’ race. Mercedes currently have the edge over Ferrari, with Lotus trailing in fourth. On the evidence of practice, Mercedes should strengthen their position in Texas. Nico Rosberg was third in the afternoon, a place ahead of his teammate Lewis Hamilton.

“This afternoon we had a very good session,” Rosberg said, according to “The car felt like it was on rails and I was very happy with the balance. I hope we can give the Red Bulls something to think about this weekend and I will be pushing 100 percent for another podium.”

Hamilton is the only active driver to have tasted victory in a Grand Prix in the U.S., having won the first race on the Austin circuit last year as well as the last time one was held in the country, in Indianapolis in 2007. But the former world champion expressed the difficulty in trying to get to the front of the grid this year.

"The weather is good, the track is getting faster, and the Red Bulls are a long way down the road but we'll still try to give them hell and catch them,” he told Sky Sports.

Certainly, it seems that Mercedes are going to face little challenge from Ferrari this weekend. The Italian team’s woes look like continuing after a disappointing second practice in which Fernando Alonso and Felipe Massa were 10th and 12th fastest, respectively.

The big story in Formula One of late, though, has been Kimi Raikkonen. The experienced former world champion, already involved in a pay dispute with his Lotus team ahead of leaving for Ferrari at the end of the year, has now had back surgery and will miss the final two races of the season. In his place, Lotus have recruited fellow-Finn Heikki Kovalainen from the Caterham team. The 32-year-old drove for Lotus in the 2010 and 2011 seasons and looked to be taking little time to get back up to speed with the car.

“It's been a pretty smooth landing, joining Lotus F1 Team,” he said. “I was able to settle in and work immediately on the set-up and tire work. All the procedures and routines are quite similar up and down the pit lane, plus I'm familiar with all the systems from driving with a Renault engine already this year and previously, so it was a pretty straightforward day."

Where to watch: Qualifying for the Formula One United States Grand Prix will get underway at 1 p.m. ET. Coverage will be provided by CNBC, with a live stream available on NBC Sports Live Extra.