SAKHIR, Bahrain -- The last time Fernando Alonso won a race was in front of his home fans at the Spanish Grand Prix two years ago.

That race is next on the Formula One calendar and given the ongoing problems at McLaren, he will be happy with a top-10 finish in Barcelona.

After four races, McLaren has not scored a point despite boasting world champions in Alonso and Jenson Button. With three weeks until the Spanish GP, things are not looking good.

Alonso's 11th-place finish in Sunday's Bahrain GP was McLaren's best performance of the season -- hardly much to shout about. But Button did not even make it out of the garage, and even if he had the 2009 F1 champion would have started from the back of the grid because of an electrical fault that also curtailed his qualifying.

"Clearly we aren't satisfied with our level of competiveness," McLaren's racing director Eric Boullier said. "We still have a mountain to climb, but climb it we will, of that you can be 100 per cent certain."

Yet Boullier remains cautious about how much will be gained from anticipated upgrades on the car in the weeks ahead.

"We'll make no predictions as where they'll place us, pace-wise, relative to our chief competitors," the Frenchman said.

Clearly, McLaren is scrambling around for answers.

The switch to Honda engines was a much-heralded move leading into the new season, with enthusiastic talk of rekindling the highly successful partnership of the late 1980s and 1990s. But problems with downforce and the power unit have put those dreams firmly on hold.

The Bahrain GP was particularly tough on Button, who spent much of the race sending tweets from his garage after being deprived of his 100th race for McLaren.

His qualifying session had been cut brutally short at the start, and he also struggled in practice -- stalling in the first session and called back to the pits for the second.

"Disappointing for all of us, and particularly for Jenson," Boullier said, explaining why Button did not start. "We believed that there was a significant likelihood that the issue would recur in running and would indeed eventually scupper Jenson's race."

The frustration has not got to the drivers quite yet, but two-time champion Alonso still spoke in the conditional sense when talking about an "eventual" improvement later in the season.

"It's clear that we're all committed to this project and to doing all we can to being about our eventual comeback," said Alonso, who has 32 career race wins. "Everyone is hugely motivated by the challenge ahead."

They will have to be.

Button has not qualified higher than 17th so far, while Alonso -- who missed the season-opener in Australia after recovering from a crash in testing -- qualified 18th in China and Malaysia.

"We'll be preparing fiercely for the first European race," said Yasuhisa Arai, Honda's chief officer of motorsport. "We'll be concentrating on competitiveness and reliability."

Alonso has not secured a podium finish since last year's Chinese GP, 19 races ago, while Button's last podium was at the 2014 season-opener in Australia.

The way things are going for McLaren, their wait is set to continue.