The upgrades that McLaren are introducing to their car at the Spanish Grand Prix will not catapult them to the front of the grid, lead driver Jenson Button has said.

The team have been off their normal, front-of-the-pack pace in 2013 and currently lie sixth in the constructors' rankings after four races.

Many teams will introduce performance upgrades in Barcelona next weekend but Button isn't getting ahead of himself.

"There'll be elements that work, elements that perhaps work in a different way than anticipated and elements that don't work. That's life," BBC Sport quotes the 2009 world champion as saying.

Button said that he hoped that returning to the Circuit de Catalunya, where two of the three pre-season tests took place, would give McLaren a better chance to assess their progress.

"It's been difficult for the team to make consistent progress in the first four races," he said.

"But I think returning to a circuit where we undertook two of the pre-season tests will give us a useful benchmark for our progress so far.

"There's been a lot of talk about the importance of next weekend's upgrades but, as with every upgrade, they're simply part of the series of continuous improvements that are made across the season."

Button himself is 10th in the drivers' rankings on 13 points, 64 adrift of leader Sebastian Vettel.