Marc Marquez says it is ‘impossible’ for him to focus on any one rider as his chief threat this season as he targets a fifth MotoGP world title.

The Repsol Honda rider leads Valentino Rossi by 27 points going into this weekend’s eighth round of the series at Assen in the Netherlands, but Marquez believes up to six riders remain in with a chance of throwing down a challenge.

Ducati’s Andrea Dovizioso began the year strongly but uncharacteristic mistakes, including a DNF last time out at Catalunya, have saw the Italian slip to eighth behind team-mate Jorge Lorenzo, who has won the last two races.

As well as Rossi, Yamaha’s Maverick Vinales and Tech 3 rider Johann Zarco are high on the championship leaderboard in third and fourth places respectively, leaving Marquez unsure over who will prove to be his main challenger as the season unfolds.

“Now it’s impossible because for me, the top five or six riders have some chance to win the championship because there are many points, many races and many different situations in front,” he said.

“But of course it looks like Yamaha riders are there, second third and fourth; Valentino is second and normally in this race track Yamaha is very fast but we will see this year. We improved this year, also Ducati is in a very good way, a good level, so we will try to defend and try to be in the fight for the victory.”

Assen TT - Memorable Moments

Marquez has finished on the podium at Assen each year since 2010, clinching four wins across the classes – one in MotoGP in 2014 – but the reigning champion says he does not need a victory on Sunday to prove that the Honda RCV is now capable of winning at every circuit.

“I’m already convinced about the team, of the bike, about myself that we are good in every circuit. We started the weekend with the mentality to fight for the victory but we will see where we arrive – it’s like we speak every Thursday: until you put the tyres on the circuit you don’t know how it will work or how will be the weekend,” he said.

“But anyway we already show that we were fast in Jerez, Le Mans, Mugello, Montmelo – different kinds of circuits and conditions. Here we expect to be competitive too.”

Marquez finished second behind Lorenzo at Catalunya to increase his title lead over Rossi, who completed the top three, on a good weekend for the factory Honda rider.

“Montmelo overall was a great weekend because we increased our advantage in the championship, which is the most important,” Marquez said.

“Then in the Monday test we did a few steps and we will try to analyse more here if it is a good step or maybe we just try to reconfirm in another race track.

“Apart of that, Assen is another race track that is a circuit that I like, especially T4 is really nice and the last part of the circuit. I enjoy it a lot and maybe it is not one of the best circuits like Austin or Sachsenring for example, but I’m quite constant here every year, I’m able to ride well, to find a good rhythm and we hope this year to continue the same progression and try to be on the podium.

“Anyway we will see and it looks like it will be sunny with a good temperature and this can change a lot.”