MONTMELO, Spain (AP) — With his pet bulldog in tow and sparkling gold chains draped over his Mercedes shirt, Lewis Hamilton struck a confident pose the day before practice starts at Formula One's Spanish Grand Prix.

Hamilton added to his reputation as one of the most eccentric characters of F1 by bringing Roscoe, one of his two bulldogs, to the packed pre-race news conference on Thursday. Roscoe was perfectly behaved, following his master through the TV cameras and photographers until he settled in under the table where Hamilton took a seat between Max Verstappen and Marcus Ericsson.

"It's great to have your pet with you," Hamilton said, before adding that Roscoe had quickly fallen asleep. "I don't think anyone in history has brought their dog to a (F1) press conference, but I like to do things differently."

The scene was befitting of the driver that entered the year as the preseason pick to lead the title race following the stunning decision of last year's champion Nico Rosberg to retire.

After all, everything had to break just right for Rosberg to finally end Hamilton's two-year run at the top in yet another duel between the Mercedes teammates, while the rest of field lagged behind.

But Hamilton arrives at the fifth race of the season facing new challengers from both within and without.

With two wins in four races, Sebastian Vettel has Ferrari oozing with confidence from the top of the points standings.

And far from installing himself as Mercedes' No. 1 driver, Hamilton has watched newcomer Valtteri Bottas pull away to an impressive debut victory at the Russian GP last round.

"I already said from the beginning of the season that (Bottas) was competition. I wasn't surprised he got the win," Hamilton said on Thursday, "(Bottas) is incredibly competitive. He was so when he joined. I think... fans came with preconceived ideas about him, and were wrong. He will remain competitive all season."

Hamilton has one win this season and two runner-up finishes to Vettel, who leads the British driver by 13 points. Bottas, meanwhile, is only 10 points behind Hamilton.

In Russia, Hamilton was out of contention well before Bottas fended off Vettel for the victory. Hamilton finished fourth, far behind Kimi Raikkonen in his Ferrari.

Hamilton said he hoped that the two-week break since Sochi will get him back on track.

"I think coming into this weekend we have a good understanding what went wrong on our side of the garage," Hamilton said. "We have grown from the experience, of having won with a strong car (for Bottas) and a car that struggled. I can't say that it will be better this weekend, but I hope so."

Vettel, for his part, was trying to cling to the role of an outside threat to Mercedes' three-year title reign.

"We are obviously in a much better position, but it is still early," Vettel said. "Mercedes are still the team to beat. Overall, they have been the dominant team and it's difficult to break that."

Vettel and Raikkonen will be aiming for another strong qualifying session on Saturday. They displayed intimidating pace during qualifying in Russia, giving the Italian outfit its first one-two race start since 2008.

Often used by teams to make major upgrades to their cars, the Spanish GP has had 10 different winners over the last decade, including Verstappen, when he became the youngest winner at age 18 last year.

Hamilton won here 2014, but his first-lap collision with Rosberg last year knocked both out of the race and marked a low point in their contentious partnership.

A year later, Hamilton must now compete on multiple fronts.