"Verstappen needs to be Hamilton-level of consistent"

Max Verstappen needs to be more consistent if he's going to challenge Lewis Hamilton in the title race in 2019, according to Merecdes engineering director, Aldo Costa.

A fantastic second half of 2018 has got people very excited about a possible title challenge from Verstappen next season, but he needs to up his consistency according to Mercedes' engneering director, who is leaving his role after seven seasons at the Silver Arrows.

Costa backed Mercedes to carry on their dominance of the sport in 2019 and has admitted he doesn't expect Verstappen to be one ot he major title contenders.

"He's a talent, he's fast but he still has to grow consistency," Costa told Italy's Gazzetta dello Sport. "That's been the winning weapon of Hamilton."

Hamilton himself believes the Red Bull Racing driver could be a major threat to his hopes of a third successive world title next season.

"If his team does the job and delivers a platform with which he can compete even closer with us, then of course he'll be in the fight," the world champion said last month.

Red Bull are making the switch to Honda to supply their power units for 2019, moving on from Renault, who they had reliability issues with; especially in 2018. Whereas Hamilton has been able to enjoy the Mercedes power unit - that was ever-reliable throughout the season.

"We have been able to bring in the second part of the season, race after race, effective developments," Costa added. "Certainly it was not a perfect year. We struggled to understand the tyres. In this respect, Red Bull was better than us. Even the reliability was good but not exceptional."