Jenson Button admitted he hopes McLaren team-mate Fernando Alonso "annihilates" him at the United States Grand Prix this weekend.

Two-time world champion Alonso was chosen to run Honda's specification four-engine upgrade for Sunday's race in Austin, while Button remains with the specification three motor.

McLaren have endured a difficult season after switching from Mercedes to Honda power units, sitting second last in the constructors' standings with four rounds to go. 

Despite both of their drivers having won world championships in the past, Alonso's fifth-place at the Hungarian Grand Prix in July was the team's best result of the season. 

Button hopes the new specification four upgrade helps catapult McLaren back up the grid. 

"Normally when you're team-mates you're on exactly the same [spec]," Button said.

"But I'm hoping it is a good upgrade that he's really quick and he annihilates me all weekend - it's unusual to say that.

"When you're fighting for a world championship or at the front, everything has to be the same. I've always pushed for that.

"But in our situation it's about getting it on the car, proving it out reliability wise, and I'll have the same engine at the next race."

Alonso was also optimistic about the upgrades, but admitted any wet-weather conditions in Austin would hamper the full results of any potential improvements. 

"From the cockpit it is difficult to feel the difference, but the data showed the improvement of the engine is as expected," Alonso said.

"This is very good news as it is a little bit of a different concept on how the engine is built, so a positive step.

"Hopefully we can use it here and exploit the performance it will give us, although obviously with the weather conditions predicted it is a little bit of a question mark on whether we can maximise the improvement."