The Monaco Grand Prix is coming up and there's quite a bit riding on it in the race for the championship.

Lewis Hamilton has opened up a lead over Sebastian Vettel at the top of the standings - something that looked quite difficult to imagine after the German took the first two races of the season.

Before the season, most believed that Mercedes were certain to continue their dominance with a fifth consecutive title, with Hamilton and team boss Toto Wolff both coming out as adamant that things were far from settled.

And it certainly looked that way after Vettel won in Australia and Bahrain but three disappointing finishes has allowed his rival to fly 17 points clear of him.

Their two teammates, Valtteri Bottas and Kimi Raikkonen sit 3rd and 4th respectively, with Red Bull's duo waiting behind.

Red Bull have had a bizarre start to the season; Max Verstappen and Daniel Ricciardo have both finished in Australia, China, and Spain but both were forced to retire in Bahrain and Azerbaijan, the latter because of a crash between the two.

Despite that, Ricciardo won in China and has set the fastest laps in both of the other races he finished, while Verstappen's 3rd place finish in Spain suggests he's back on track.

And it's for those reasons that Lewis Hamilton envisions a difficult race this weekend.

“We came from the last race knowing this is going to be one of the tougher races for us,” Hamilton said ahead of Monaco. “If you look at the last race and even in testing in February and even the test the other day, the Red Bulls were particularly quick in the last sector - that’s where they’re always very, very strong.

"So you can imagine that they will be incredibly quick here this weekend, which is actually a surprise on previous years, because Ferrari were very strong last year and for whatever reason, Red Bull didn’t get it together but maybe this weekend they will.

“I do anticipate it’s going to be a difficult weekend - not one that is impossible but it’s a lot closer and we may not have the pace of the others."

But despite his worries, Hamilton certainly doesn't write off his chances of extending his lead.

“But we will find out tomorrow the true pace and identity of what we arrive here with," he said. "I’m excited for the challenge.

"If you look at last year, there were overcuts and undercuts so anything is possible.”