Sebastian Vettel: Red Bull can close the gap on Mercedes

Sebastian Vettel believes Red Bull can catch Mercedes this season after an improved display by the reigning world champions at the Spanish Grand Prix.

Vettel, 26, claimed fourth, with team-mate Daniel Ricciardo finishing third behind the Mercedes duo of Nico Rosberg and race winner Lewis Hamilton.

"We are here to fight for the championship," said Vettel.

"Hopefully in time we can catch up and give them a run for their money."

Vettel had started 15th on the grid after receiving a five-place penalty because of a gearbox change, but cut through the field to claim his second highest-finish of the season.

It was a welcome result for the German after what had been a troubled weekend in Barcelona, which started with an electrical problem that curtailed his involvement in practice on Friday, and included the failed gearbox during qualifying on Saturday.

Vettel is fourth in the championship with 45 points, 55 behind leader Hamilton.

"I enjoyed the race and third and fourth is the best we could get," added Vettel.

"Mercedes is very strong, they have a phenomenal engine, a very good car and two very good drivers.

"They deserve to be in that position, but from our point of view we hope that their dominance can come to an end."

Ricciardo, whose podium finish was officially the first of his career following his disqualification from second at the Australian Grand Prix, feels it will be a little more difficult to catch the Mercedes, but shares his team-mate's belief that Red Bull can close the gap in time.

He said: "I think we need a lasso onto the back of the Mercedes and let them tow us along."

Ferrari driver Fernando Alonso says the performance gap between Mercedes and the other teams is "amazing".

The Spanish double world champion described a "tough" race where he struggled with "low grip" to finish sixth.

"We struggled with the start and did not make any places on the first corner and we were stuck in traffic for 90% of the race," he said.

Alonso had spent the first stint of the race stuck at the back of a three-car train led by Lotus' Romain Grosjean and Ferrari team-mate Kimi Raikkonen.

Alonso made his first pit stop a lap earlier in an attempt to pass the Finn, which is against normal protocol.

The driver leading on the track usually gets first-call on pit-stop timing.

But the tactic failed when Alonso hit traffic on his out lap, forcing the Spaniard into an extra pit stop later in the race.

Raikkonen, who finished seventh after being passed by Alonso late in the race, appeared to question Ferrari's strategy on the radio on the slowing-down lap, asking "who made these calls" and suggesting he "seemed to be getting second choice".

Afterwards, Raikkonen admitted he had "wanted to clarify a few things".

It was largely another race to forget for McLaren as both Jenson Button, who finished 11th, and Kevin Magnussen, who took 12th, failed to finish inside the points for the third successive race.

Button, world champion in 2009, believes he and his team took away an important lesson from the weekend.

"If we got everything together, we might have finished 10th but the start cost us," he said.