Mercedes racer Lewis Hamilton has admitted that he has no idea as to what the reasons are for his side's poor performance at the Spanish Grand Prix on Sunday.

The Brit along with teammmate Nico Rosberg started at second and first respectively on the grid, but ended up finishing 12th and ninth respectively in what turned out to be a day to forget for the Silver Arrows.

Hamilton, who was lapped during the race, has no explanation as to why he endured such a disappointing race in Barcelona.

"It was an experience I don't want to go through again," Hamilton told Sky Sports News. "I don't know why it happened.

"I did absolutely everything I did in Bahrain but the tyres just didn't come in and give me any grip. If I pushed, they went off immediately.

"I'm absolutely lost, I don't know what went wrong. It seems like others have made a bigger step forwards than we did. If anything, it seems like we didn't make a step forward even though we brought upgrades because we didn't fix the problems of degradation."

Hamilton has slipped to fourth in the drivers' rankings following the race.