Formula 1 World Championship leader Fernando Alonso has declared that he won't be able to maintain his lead unless his Ferrari makes a vast improvement.

Alonso heads the standings despite not gaining a single pole position in the opening six races of the season.

The Spaniard is aware of the need to find pace and consistency if he is to maintain a title challenge in a hotly contested driver's championship.

"As long as there are different winners in races, you need to be consistent if you want to lead the championship," Alonso said. "On Sundays we are normally are a little bit more competitive. We take advantage of the experience from the team and the talent from the team in terms of preparation for the race, the starts, and the strategy.

"But we know that we are not fast enough, especially on Saturday when we are all in the same conditions, with low fuel and new tyres. We are struggling to be in Q3 [final qualifying] sometimes and we are not anywhere close to pole position. With that, that we are now leading the championship is something that we cannot maintain if we are not quick enough.

"We are not the fastest on the track. So that is something that we need to look for and hopefully [here] in Canada we will see another step forward from the team and we are close again to the top guys. But we will not know until after qualifying."

Alonso will be hoping to break Ferrari's qualifying duck this weekend in what promises to be a highly competitive Canadian Grand Prix.