Fernando Alonso believes he must be considered as one of the finest Formula One drivers of all time on the eve of his 300th grand prix.

Alonso, 37 next month, will become only the fourth driver in history to reach the milestone here in Canada on Sunday.

"I am one of the best to have raced in F1," Alonso said.

"I am probably not the fastest driver in qualifying. I'm probably not the fastest driver in the race, or in wet conditions, but I am a 9.5 in all areas, and I try to benefit from that."

Along with Lewis Hamilton, Alonso is viewed as the greatest of his generation, but it has been more than five years since he won a race, while he toasted the last of his two successive titles in 2006. Remarkably, Hamilton has double the tally of Alonso's victories: 64 plays 32.

Alonso's career is rather a case of what might have been after a catalogue of rows, and ill-advised moves.

He was signed by McLaren from Renault as the two-time world champion in 2007, but he departed after just one season following bitter fall-outs with Hamilton and the team's long-serving chairman Ron Dennis.

Alonso appeared to resurrect his title hopes with a move to Ferrari, but after he was beaten by Sebastian Vettel at the season-concluding races in 2010 and 2012, he was shown the door after the Italians grew frustrated with him.

Alonso opted for another term at McLaren, but his second spell has been disastrous. Alonso has got the very best out of an under-performing car, but he knows he may probably never win again.

"There are some opportunities missing," Alonso added. "I could have won four or five championships, but at the same time I feel extremely privileged to have had 18 years in F1.

"I have a lot of good memories. There have been a lot of ups and downs, but winning my two championships was definitely the high point."

Alonso will contest the Le Mans 24 Hours race next weekend as he bids to emulate Graham Hill's 'Triple Crown' – which also includes the Monaco Grand Prix (a race Alonso has won twice) and the Indianapolis 500 (where Alonso excelled on his debut last year, before a late engine blow-up cost him dearly).

F1 has taken a back seat for the Spaniard, but despite three years of turmoil at McLaren, Alonso remained for another campaign in the hope that their divorce from Honda and switch to Renault would fire Britain's most successful team back to the front.

But McLaren still remain a shadow of their former selves, and only Alonso's brilliance has enabled him to collect 32 points and lie seventh in the standings.

"No, I'm not bored," said Alonso, who will later this summer decide whether to extend his £20m-a-year-contract into another campaign.

"It's obviously the top series in motorsport, and it's where we all dream to come, but it's true that in the last years it is so predictable.

"This is race seven – there are 21 races – and we all know what is going to happen. You can play basketball, and have a magic night and score 40 points with your team-mates and win the game.

"There are favourites for the World Cup, but you can't guarantee Germany, Spain or Brazil will win, but here everyone can guarantee that Mercedes or Ferrari will win the race, and this is very sad for the sport."

Max Verstappen, meanwhile, edged out championship leader Hamilton in opening practice for the Sunday's grand prix.

Verstappen had threatened to headbutt someone if he continued to be quizzed about his error-prone campaign on Thursday, but the 20-year-old Dutchman allowed his driving to do the talking in the first running of the weekend at the Circuit Gilles-Villeneuve.

Verstappen set a best lap of one minute and 13.302 seconds to finish clear of Hamilton, with Daniel Ricciardo third in the other Red Bull.

Ferrari's Vettel, who trails Hamilton by 14 points in the championship race, was fourth in Montreal.

Hamilton admitted on Thursday that he fears he may not be in contention for the victory this weekend after his Mercedes team failed to bring a scheduled engine update with them to North America.

It means Hamilton, 33, is set to be down on power, while continuing with an engine that he has used at every round since the opening rubber in Australia. In contrast, Vettel has been afforded the luxury of a fresh Ferrari power unit.

But Hamilton, who is chasing a record-equalling seventh win in Montreal, was just nine hundredths of a second down on Verstappen, and ahead of his title rival Vettel.