Red Bull Racing's team principal Christian Horner says Jenson Button cannot afford to continue with his streak of poor results if he is to win the championship this year.
The British driver won six of the first seven races of the season but has not been on the podium in the last five and retired for the first time at the Belgian Grand Prix last Sunday. Teammate Rubens Barrichello is now 16 points behind, with Red Bull's Sebastian Vettel 19 adrift.
Both drivers have been stronger than Button in recent races, as the Briton has struggled to show competitive pace with his Brawn car. Horner reckons Button will need to find his form soon if he wants to stay on top of the championship table.
"Rubens has taken 10 points out of him in the last two races and Sebastian six points here, and he's not had a good weekend since Istanbul in early June," Horner said. "He can't continue to have race weekends like he's had without being punished, points wise, in the next couple of events.
"It's still a four-horse race between now and the end of the championship."
Horner is adamant that both Vettel and Mark Webber are still very much in the hunt for the title.
"It's all left to play for, and I think there's going to be another twist in the championship between now and the end of the year," he added. "Sebastian has moved to within 19 points, and although Mark didn't score, both still have a real chance of overhauling over him."
The Red Bull boss made it clear, however, that the team has no plans to support just one of its drivers yet.
"With one-and-a-half-points between the drivers it would be wrong at this stage to back one over the other. We'll continue to do what we've done all year and support both of them with equal priority."